Author Archives: netchild

About netchild

A FreeBSD committer.

Updating FreeBSD 8.2 (or 9.x) to 10 (beta4)

This is a little description how I remotely (no console, booted into multi-user during update, no external services like jails/httpd/… running) updated a FreeBSD 8.2 to 10 (beta4) from source. This should also work when updating from FreeBSD 9.x. Note, I had already switched to ATA_CAM on 8.2, so not instructions for the name change of the ata devices. No IPv6, WLAN or CARP is in use here, so changes which are needed in this area are not covered. Read UPDATING carefully, there are a lot of changes between major releases.

What I did:

  • update /usr/src
  • make buildworld
  • replace “make ” in /usr/src/Makefile.inc1 with ${MAKE} (two times, one for “VERSION”, one for “BRANCH”)
  • verify kernel config for changes needed (running “config MyKernel” in /usr/src/sys/YourArch/conf/ helps to identify syntax problems), sorry I didn’t take notes, but I diffed the old and the new GENERIC config and added/removed according to my interests
  • /usr/obj/…/src/usr.bin/bmake/make buildkernel KERNCONF=MyKernel
  • /usr/obj/…/src/usr.bin/bmake/make installkernel KERNCONF=MyKernel KODIR=/boot/kernel.10
  • mergemaster –p
  • /usr/obj/…/src/usr.bin/bmake/make installworld DESTDIR=/somewhere/test
  • mkdir /root/net10; cp /somewhere/test/rescue/ifconfig /somewhere/test/rescue/route /root/net10
  • create the file /etc/rc.10update with:
    case $(uname –r) in
    8.2*)
            MYIFCONFIG=/sbin/ifconfig
            MYROUTE=/sbin/route
            ;;
    10*)
            MYIFCONFIG=/root/net10/ifconfig
            MYROUTE=/root/net10/route
            ;;
    esac
    export MYIFCONFIG
    export MYROUTE
  • change the files (stupid approach: grep for “ifconfig” and “route” in /etc/rc.d to identify files which need to change, I skipped files which I identified as not needed in my case, if you use pf/IPv6/bridge/…, you may have to change some more files) /etc/rc.d/auto_linklocal /etc/rc.d/defaultroute /etc/rc.d/netif /etc/rc.d/netwait /etc/rc.d/routing: add “. /etc/rc.10update” at the end of the block with “. /etc/rc.subr”, change the “ifconfig”-command to ${MYIFCONFIG}, change the “route”-command to ${MYROUTE}
  • change /etc/network.subr: add “. /etc/rc.10update” before the first function, change the “ifconfig”-command to ${MYIFCONFIG}, change the “route”-command to ${MYROUTE}
  • make sure that the changes you made are 100% correct, rather triple-check than to not check at all (you will be locked out if they are not 100% OK)
  • stop any jails and make sure they do not restart at boot
  • deactivate the gmirror of the root-fs, if there is one (it is maybe easier to ask a remote hand to swap the boot order in case of problems)
  • here you could just a reboot of the server to come back to your current OS version, so make sure that the modifications in /etc did not cause any problems with the old version (in case you see problems with the v10 kernel), but if you do not have a remote console to single-user mode you have no chance to directly fix the problem (risk mitigation described above), no matter which version of the kernel you boot
  • nextboot –k kernel.10
  • shutdown –r now
  • login
  • check dmesg
  • optional: mv /boot/kernel /boot/kernel.8
  • make installkernel KERNCONF=MyKernel
    to have a v10 /boot/kernel
  • make installworld
  • mergemaster
  • make delete-old
  • rm –r /etc/rc.10update /root/net10
  • change rc.conf: add “inet” in ifconfig-aliases
  • review sysctl.conf for outdated entries
  • shutdown –r now
  • optional: rm –r /boot/kernel.10
  • enable jails again (or later… updating jails is not described here)
  • activate/resync mirror(s)
  • rebuild all ports (attention: new pkg system)
  • make delete-old-libs
  • reboot again to make sure everything is OK after the port-rebuild and removal of old libs (a console.log (syslog.conf) helps here

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Lin­ux­u­la­tor explained: How to create Linux binaries on FreeBSD

There may by cases where you want to generate a Linux binary on a FreeBSD machine. This is not a problem with the linuxulator, but not with the default linux_base port.

As you may know, the linux_base port is designed to deliver an integrated experience with FreeBSD native programs. As such some parts of the native FreeBSD infrastructure is used. If you would try to use a Linux–compiler to generate Linux–binaries, you would run into the problem that by default the FreeBSD includes are used.

Prerequisites

To have a fully featured and non-integrated Linux environment on your FreeBSD system either mount an existing (and compatible) Linux installation somewhere into your FreeBSD system, or install a linux_dist port. This can be done additionally to an already installed linux_base port.

Preparation

When you have a complete Linux environment available, you need to mount the FreeBSD devfs to /path/to/complete_linux/dev, linprocfs to /path/to/complete_linux/proc and linsysfs to /path/to/complete_linux/sys to have a complete setup.

Use it

Now you just need to chroot into this  /path/to/complete_linux and you configure/make/install or whatever you need to do to generate your desired Linux binary.

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Which crypto card to use with FreeBSD (ssh/gpg)

The recent security incident triggered a discussion how to secure ssh/gpg keys.

One way I want to focus on here (because it is the way I want to use at home), is to store the keys on a crypto card. I did some research for suitable crypto cards and found one which is called Feitian PKI Smartcard, and one which is called OpenPGP card. The OpenPGP card also exists in a USB version (basically a small version of the card is already integrated into a small USB card reader).

The Feitian card is reported to be able to handle RSA keys upto 2048 bits. They do not seem to handle DSA (or ECDSA) keys. The smartcard quick starter guide they have  (the Tuning smartcard file system part) tells how to change the parameters of the card to store upto 9 keys on it.

The spec of the OpenPGP card tells that it supports RSA keys upto 3072 bits, but there are reports that it is able to handle RSA keys upto 4096 bits (you need to have at least GPG 2.0.18 to handle that big keys on the crypto card). It looks to me like the card is not handle DSA (or ECDSA) cards. There are only slots for upto 3 keys on it.

If I go this way, I would also need a card reader. It seems a class 3 one (hardware PIN pad and display) would be the most “future-proof” way to go ahead. I found a Reiner SCT cyberJack secoder card reader, which is believed to be supported by OpenSC and seems to be a good balance between cost and features of the Reiner SCT card readers.

If anyone reading this can suggest a better crypto card (keys upto 4096 bits, more than 3 slots, and/or DSA/ECDSA  support), or a better card reader, or has any practical experience with any of those components on FreeBSD, please add a comment.

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Hats off to the people handling the recent security incident

I pull my hat to the people handling the recent security incident on the FreeBSD infrastructure.

Guys:

  • Thanks a lot for the countless hours you invested to find and close the initial attack vector.
  • Thanks a lot for the countless hours you invested to get the machines back to a well known state.
  • Thanks a lot for the countless hours you invested to verify the source repository.
  • Thanks a lot for the countless hours you invested to get back to a trusted package building environment.
  • Thanks a lot for the countless hours you invested to get the “remaining” infrastructure (and everything else I forgot to mention) back into a good state.

Or in short: Thanks a lot for the countless hours you invested to get us from “we’re busted” to “we’re back”.

And last but not least, thanks for the decision to be better safe than sorry regarding our userbase (while it is the only way to handle something like this in a OSS project, I unfortunately think it has to be mentioned instead of taking it as an obvious decision).

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Book review: FreeBSD Device Drivers

In mid-April a woman from the marketing department of No Starch Press contacted me and asked if I am interested to do a public review of the FreeBSD Device Drivers book by Joseph Kong (no link to a book shop, go and have a look in your preferred one). Just this simple question, no strings attached.

I had my nose in some device drivers in the past, but I never wrote one, and never had a look at the big picture. I was interested to know how everything fits together, so this made me a good victim for a review (novice enough to learn something new and to have a look if enough is explained, and experienced enough to understand what is going on in the FreeBSD kernel).

Some minutes after I agreed to review it (but with a little notice that I do not know how long I need to review it), I had the PDF version of the book. That was faster than I expected (maybe I am too old-school and used to have paper versions of books in my hands).

Let the review begin… but bear with me, this is the first time I do a real public review of a book (instead of a technical review for an author). And as this is my very own personal opinion, I will not allow comments here. This page is all about my opinion while reading the book, questions I have while reading the book shall serve as a hint about the quality of the book and they should be answered in the book, not here.

In short, the book is not perfect, but it is a good book. There is room for improvement, but on a very high level. If you want to write a device driver for FreeBSD, this book is a must. I suggest to read it completely, even chapters which do not belong to the type of driver you want to write (specially the case studies of real drivers). The reason is that each chapter has some notes which may not only apply to the chapter in question, but to all kinds of device drivers. The long review follows now.

The first chapter is titled “Building and running modules”. The author begins with description of the usual device driver types (NIC driver, pseudo-device, …) and how they can be added to the kernel (statically linked in or as a module). The first code example is a small and easy kernel module, so that we do not have to reboot the system we use to develop a driver (except we make a fault during driver development which causes the machine to panic or hang). Every part of the example is well explained. This is followed by an overview about character devices (e.g. disks) and a simple character-device driver (so far a pseudo-device, as we do not have real hardware we access) which is not only as-well explained as the module-example, but there is also a note where the code was simplified and what should be done instead.

After reading this chapter you should be able to write your own kernel module in 5 minutes (well, after 5 minutes it will not be able to do a lot — just a “hello world” – but at least you can already load/unload/execute some code into/from/in the kernel).

I have not tried any example myself, but I compiled a lot of modules and drivers I modified in the past and remember to have seen the described parts.

The second chapter explains how to allocate and free memory in the kernel. There is the possibility to allocate maybe-contiguous memory (the normal case, when your hardware does not do DMA or does not have the requirement that the memory region it makes DMA from/too needs to be contiguous), and really contiguous. For the size argument of the freeing of the the contiguous memory there is the sentence “Generally, size should be equal the amount allocated.”. Immediately I wanted to know what happens if you specify a different size (as a non-native english speaker I understand this sentence in a way that I am allowed to specify a different size and as such are able to free only parts of the allocated memory). Unfortunately this is not answered. I had a look into the source, the kernel frees memory pages, so the size argument (and addr argument) will be rounded to include a full page. This means theoretically I am able to free parts of the allocated memory, but this is a source-maintenance nightmare (needs knowledge about the machine specific page boundaries and you need to make sure that you do the absolutely correct size calculations).  To me this looks more like as long as nobody is pointing a gun at my head and tells me to use a different size, specifying the same size as made during the allocation of this memory region is the way to go.

After reading this chapter you should know how to kill the system by allocating all the RAM in the kernel.

Again, I did not try to compile the examples in this chapter, but the difference of the memory allocation in the kernel compared with memory allocation in the userland is not that big.

The third chapter explains the device communication and control interfaces (ioctl/sysctl) of a driver. The ioctl part teached me some parts I always wanted to know when I touched some ioctls, but never bothered to find out before. Unfortunately this makes me a little bit nervous about the way ioctls are handled in the FreeBSD linuxulator, but this is not urgent ATM (and can probably be handled by a commend in the right place). The sysctl part takes a little bit longer to follow through, but there is also more to learn about it. If you just modify an existing driver with an existing sysctl interface, it probably just comes down to copy&paste with little modifications, but if you need to make more complex changes or want to add a sysctl interface to a driver, this part of the book is a good way to understand what is possible and how everything fits together. Personally I would have wished for a more detailed guide when to pick the ioctl interface and when the sysctl interface than what was written in the conclusion of the chapter, but it is probably not that easy to come up with a good list which fits most drivers.

After reading this chapter you should be able to get data in and out of the kernel in 10 minutes.

As before, I did not compile the examples in this chapter. I already added ioctls and sysctls in various places in the FreeBSD kernel.

Chapter 4 is about thread synchronization – mutexes, shared/exclusive locks, reader/writer locks and condition variables. For me this chapter is not as good as the previous ones. While I got a good explanation of everything, I missed a nice overview table which compares the various methods of thread synchronization. Brendan Gregg did a nice table to give an overview of DTrace variable types and when to use them. Something like this would have been nice in this chapter too. Apart from this I got all the info I need (but hey, I already wrote a NFS client for an experimental computer with more than 200000 CPUs in 1998, so I’m familiar with such synchronization primitives).

Delayed execution is explained in chapter 5. Most of the information presented there was new to me. While there where not much examples presented (there will be some in a later chapter), I got a good overview about what exists. This time there was even an overview when to use which type of delayed execution infrastructure. I would have preferred to have this overview in the beginning of the chapter, but that is maybe some kind of personal preference.

In chapter 6 a complete device driver is dissected. It is the virtual null modem terminal driver. The chapter provides real-world examples of event-handlers, callouts and taskqueues which where not demonstrated in chapter five. At the same time the chapter serves as a description of the functions a TTY driver needs to have.

Automated device detection with Newbus and the corresponding resource allocation (I/O ports, device memory and interrupts) are explained in chapter 7. It is easy… if you have a real device to play with. Unfortunately the chapter missed a paragraph or two about the suspend and resume methods. If you think about it, it is not hard to come up with what they are supposed to do, but a little explicit description of what they shall do, in what state the hardware should be put and what to assume when being called would have been nice.

Chapter 8 is about interrupts. It is easy to add an interrupt handler (or to remove one), the hard part is to generate an interrupt. The example code uses the parallel port, and the chapter also contains a little explanation how to generate an interrupt… if you are not afraid to touch real hardware (the parallel port) with a resistor.

In chapter 9 the lpt(4) driver is explained, as most of the topics discussed so far are used inside. The explanation how everything is used is good, but what I miss sometimes is why they are used. The most prominent (and only) example here for me is why are callouts used to catch stray interrupts? That callouts are a good way of handling this is clear to me, the big question is why can there be stray interrupts. Can this happen only for the parallel port (respectively a limited amount of devices), or does every driver for real interrupt driven hardware need to come with something like this? I assume this is something specific to the device, but a little explanation regarding this would have been nice.

Accessing I/O ports and I/O memory for devices are explained in chapter 10 based upon a driver for a LED device (turn on and off 2 LEDs on an ISA bus). All the functions to read and write data are well explained, just the part about the memory barrier is a little bit short. It is not clear why the CPU reordering of memory accesses matter to what looks like function calls. Those function calls may be macros, but this is not explained in the text. Some little examples when to use the barriers instead of an abstract description would also have been nice at this point.

Chapter 11 is similar to chapter 10, just that a PCI bus driver is discussed instead of an ISA bus driver. The differences are not that big, but important.

In chapter 12 it is explained how to do DMA in a driver. This part is not easy to understand. I would have wanted to have more examples and explanations of the DMA tag and DMA map parts. I am also surprised to see different supported architectures for the flags BUS_DMA_COHERENT and BUS_DMA_NOCACHE for different functions. Either this means FreeBSD is not coherent in those parts, or it is a bug in the book, or it is supposed to be like this and the reasons are not explained in the book. As there is no explicit note about this, it probably leads to confusion of readers which pay enough attention here. It would also have been nice to have an explanation when to use those flags which are only implemented on a subset of the architectures FreeBSD supports. Anyway, the explanations give enough information to understand what is going on and to be able to have a look at other device drivers for real-live examples and to get a deeper understanding of this topic.

Disk drivers and block I/O (bio) requests are described in chapter 13. With this chapter I have a little problem. The author used the word “undefined” in several places where I as a non-native speaker would have used “not set” or “set to 0″. The word “undefined” implies for me that there may be garbage inside, whereas from a technical point of view I can not imagine that some random value in those places would have the desired result. In my opinion each such place is obvious, so I do not expect that an experienced programmer would lose time/hairs/sanity over it, but inexperienced programmers which try to assemble the corresponding structures on the (uninitialized) heap (for whatever reason), may struggle with this.

Chapter 14 is about the CAM layer. While the previous chapter showed how to write a driver for a disk device, chapter 14 gave an overview about how to an HBA to the CAM layer. It is just an overview, it looks like CAM needs a book on its own to be fully described. The simple (and most important) cases are described, with the hardware-specific parts being an exercise for the person writing the device driver. I have the impression it gives enough details to let someone with hardware (or protocol), and more importantly documentation for this device, start writing a driver.

It would have been nice if chapter 13 and 14 would have had a little schematic which describes at which level of the kernel-subsystems the corresponding driver sits. And while I am at it, a schematic with all the driver components discussed in this book at the beginning as an overview, or in the end as an annex, would be great too.

An overview of USB drivers is given in chapter 15 with the USB printer driver as an example for the explanation of the USB driver interfaces. If USB would not be as complex as it is, it would be a nice chapter to start driver-writing experiments (due to the availability of various USB devices). Well… bad luck for curious people. BTW, the author gives pointers to the official USB docs, so if you are really curious, feel free to go ahead. :)

Chapter 16 is the first part about network drivers. It deals with ifnet (e.g. stuff needed for ifconfig), ifmedia (simplified: which kind of cable and speed is supported), mbufs and MSI(-X). As in other chapters before, a little overview and a little picture in the beginning would have been nice.

Finally, in chapter 17, the packet reception and transmission of network drivers is described. Large example code is broken up into several pieces here, for more easy discussion of related information.

One thing I miss after reaching the end of the book is a discussion of sound drivers. And this is surely not the only type of drivers which is not discussed, I can come up with crypto, firewire, gpio, watchdog, smb and iic devices within a few seconds. While I think that it is much more easy to understand all those drivers now after reading the book, it would have been nice to have at least a little overview of other driver types and maybe even a short description of their driver methods.

Conclusion: As I wrote already in the beginning, the book is not perfect, but it is good. While I have not written a device driver for FreeBSD, the book provided enough insight to be able to write one and to understand existing drivers. I really hope there will be a second edition which addresses the minor issues I had while reading it to make it a perfect book.

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Algorithm to detect repo-copies in CVS

FreeBSD is on its way to move from CVS to SVN  for the version control system for the Ports Collection. The decision was made to keep the complete history, so the complete CVS repository has to be converted to SVN.

As CVS has no way to record a copy or move of files inside the repository, we copied the CVS files inside the repository in case we wanted to copy or move a file (the so called “repocopy”). While this allows to see the full history of a file, the drawback is that you do not really know when a file was copied/moved if you are not strict at recording this info after doing a copy. Guess what, we where not.

Now with the move to SVN which has a build-in way for copies/moves, it would be nice if we could record this info. In an internal discussion someone told its not possible to detect a repocopy reliably.

Well, I thought otherwise and an hour later my mail went out how to detect one. The longest time was needed to write how to do it, not to come up with a solution. I do not know if someone picked up this algorithm and implemented something for the cvs2svn converter, but I decided to publish the algorithm here if someone needs a similar functionality somewhere else. Note, the following is tailored to the structure of the Ports Collection. This allows to speed up some things (no need to do all steps on all files). If you want to use this in a generic repository where the structure is not as regular as in our Ports Collection, you have to run this algorithm on all files.

It also detects commits where multiple files where committed at once in one commit (sweeping commits).

Preparation

  • check only category/name/Makefile
  • generate a hash of each commitlog+committer
  • if you are memory-limited use ha/sh/ed/dirs/cvs-rev and store pathname in the list cvs-rev (pathname = “category-name”) as storage
  • store the hash also in pathname/cvs-rev

If you have only one item in ha/sh/ed/dirs/cvs-rev in the end, there was no repocopy and no sweeping commit, you can delete this ha/sh/ed/dirs/cvs-rev.

If you have more than … let’s say … 10 (subject to tuning) pathnames in ha/sh/ed/dirs/cvs-rev you found a sweeping commit and you can delete the ha/sh/ed/dirs/cvs-rev.

The meat

The remaining ha/sh/ed/dirs/cvs-rev are probably repocopies. Take one ha/sh/ed/dirs/cvs-rev and for each pathname (there may be more than 2 pathnames) in there have a look at pathname/. Take the first cvs-rev of each and check if they have the same hash. Continue with the next rev-number for each until you found a cvs-rev which does not contain the same hash. If the number of cvs-revs since the beginning is >= … let’s say … 3 (subject to tuning), you have a candidate for a repocopy. If it is >=  … 10 (subject to tuning), you have a very good indicator for a repocopy. You have to proceed until you have only one pathname left.

You may detect multiple repocopies like A->B->C->D or A->B + A->D + A->C here.

Write out the repocopy candidate to a list and delete the ha/sh/ed/dirs/cvs-rev for each cvs-rev in a detected sequence.

This finds repocopy candidates for category/name/Makefile. To detect the correct repocopy-date (there are maybe cases where another file was changed after the Makefile but before the repocopy), you now have to look at all the files for a given repocopy-pair and check if there is a matching commit after the Makefile-commit-date. If you want to be 100% sure, you compare the complete commit-history of all files for a given repocopy-pair.

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Alexander Leidinger

A while ago I committed the linuxulator D-Trace probes I talked about earlier. I waited a little bit for this announcement to make sure I have not broken anything. Nobody complained so far, so I assume nothing obviously bad crept in.

The >500 probes I committed do not cover the entire linuxulator, but are a good start. Adding new ones is straight forward, if someone is interested in a junior–kernel–hacker task, this would be one. Just ask me (or ask on emulation@), and I can guide you through it.

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Alexander Leidinger

Seems I forgot to announce that the linux_base-c6 is in the Ports Collection now. Well, it is not a replacement for the current default linux base, the linuxulator infrastructure ports are missing and we need to check if the kernel supports enough of 2.6.18 that nothing breaks.

TODO:

To my knowledge, nobody is working on anything of this. Anyone is welcome to have a look and provide patches.

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Alexander Leidinger

In case you have not noticed yet, KDTRACE_HOOKS is now in the GENERIC kernel in FreeBSD-current. This means you just need to load the DTrace modules and can use DTrace with the GENERIC kernel.

In case you do not know what you can do with DTrace, take the time to have a look at the DTrace blog. It is worth any minute you invest reading it.

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Alexander Leidinger

This weekend I made some progress in the linuxulator:

  • I MFCed the reporting of some linux-syscalls to 9-stable and 8-stable.
  • I updated my linuxulator-dtrace patch to a recent -current. I already compiled it on i386 and arundel@ has it compiled on amd64. I counted more than 500 new DTrace probes. Now that DTrace rescans for SDT probes when a kernel module is loaded, there is no kernel panic anymore when the linux module is loaded after the DTrace modules and you want to use DTrace. I try to commit this at a morning of a day where I can fix things during the day in case some problems show up which I did not notice during my testing.
  • I created a PR for portmgr@ to repocopy a new linux_base port.
  • I set the expiration date of linux_base-fc4 (only used by 7.x and upstream way past its EoL) and all dependent ports. It is set to the EoL of the last 7.x release, which can not use a later linux_base port. I also added a comment which explains that the date is the EoL of the last 7.x release.

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Alexander Leidinger

I just updated to a recent -current and tried the new nullfs. Sockets (e.g. the MySQL one) work now with nullfs. No need to have e.g. jails on the same FS and hardlink the socket to not need to use TCP in MySQL (or an IP at all for the jail).

Great work!

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New CentOS linux_base for testing soonish

It seems my HOWTO create a new linux_base port was not too bad. There is now a PR for a CentOS 6 based linux_base port. I had a quick look at it and it seems that it is nearly usable to include into the Ports Collection (the SRPMs need to be added, but that can be done within some minutes).

When FreeBSD 8.3 is released and the Ports Collection open for sweeping commits again, I will ask portmgr to do a repo-copy for the new port and commit it. This is just the linux_base port, not the complete infrastructure which is needed to completely replace the current default linuxulator userland. This is just a start. The process of switching to a more recent linux_base port is a long process, and in this case depends upon enough support in the supported FreeBSD releases.

Attention: Anyone installing the port from the PR should be aware that using it is a highly experimental task. You need to change the linuxulator to impersonate himself as a linux 2.6.18 kernel (described in the pkg-message of the port), and the code in FreeBSD is far from supporting this. Anyone who wants to try it is welcome, but you have to run FreeBSD-current as of at least the last weekend, and watch out for kernel messages about unsupported syscalls. Reports to [email protected] please, not here on the webpage.

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New opportunities in the linuxulator

Last weekend I committed some dummy-syscalls to the linuxulator in FreeBSD-current. I also added some comments to syscalls.master which should give a hint which linux kernel had them for the first time (if the linux man–page I looked this up in is correct). So if someone wants to experiment with a higher compat.linux.osrelease than 2.6.16 (as it is needed for a CentOS based linux_base), he should now get some kernel messages about unimplemented syscalls instead of a silent failure.

There may be some low-hanging fruits in there, but I did not really verify this by checking what the dummy syscalls are supposed to do in linux and if we can easily map this to existing FreeBSD features. In case someone has a look, please send an email to emulation@FreeBSD.org.

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Static DTrace probes for the linuxulator updated

I got a little bit of time to update my 3 year old work of adding static DTrace probes to the linuxulator.

The changes are not in HEAD, but in my linuxulator-dtrace branch. The revision to have a look at is r230910. Included are some DTrace scripts:

  • script to check internal locks
  • script to trace futexes
  • script to generate stats for DTracified linuxulator parts
  • script to check for errors:
    • emulation errors (unsupported stuff, unknown stuff, …)
    • kernel errors (resource shortage, …)
    • programming errors (errors which can happen if someone made a mistake, but should not happen)

The programming-error checks give hints about userland programming errors respectively a hint about the reason of error return values due to resource shortage or maybe a wrong combination of parameters. An example error message for this case is “Application %s issued a sysctl which failed the length restrictions.nThe length passed is %d, the min length supported is 1 and the max length supported is %d.n

More drivers available in the FreeBSD-kernel doxygen docs

Yesterday I committed some more configs to generate doxygen documentation of FreeBSD-kernel drivers. I mechanically generated missing configs for subdirectories of src/sys/dev/. This means there is no dependency information included in the configs, and as such you will not get links e.g. to the PCI documentation, if a driver calls functions in the PCI driver (feel free to tell me about such dependencies).

If  you want to generate the HTML or PDF version of some subsystem, just go to src/tools/kerneldoc/subsys/ an run “make

How to fix FreeBSD for corporations (and user with smaller installations), the tools-viewpoint

There is a huge discussion going on on hackers@ about how FreeBSD is not suitable for large installations (anymore?). As of this writing, the discussion seems to get some discussion-clusters. We have some sub-topics which could lead to some good improvements.

One subtopic is the release engineering. Some changes like a more guided approach of what should be merged to which branch, the frequency of releases and maybe some kind of long-term-branch(es). There is some discussion to get maybe some joined-funding in some way from interested parties to pay someone to take care about long-term-branch(es).

Another subtopic is the way bugs are handled in our old bugtracking software and how patches go unnoticed there.

And both of them are connected (parts more, parts less) by what can be done in a volunteer project.

To me it looks like the proposals “just

Tuning guide in the wiki

In the light of the recent benchmark discussion, a volunteer imported the tuning man-page into the wiki. Some comments at some places for possible improvements are already made. Please go over there, have a look, and participate please (testing/verification/discussion/improvements/…).

As always, feel free to register with FirstnameLastname and tell a FreeBSD committer to add you to the contributors group for write access (you also get the benefit to be able to register for an email notification for specific pages).

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A phoronix benchmark creates a huge benchmarking discussion

The recent Phoronix benchmark which compared a release candidate of FreeBSD 9 with Oracle Linux Server 6.1 created a huge discussion in the FreeBSD mailinglists. The reason was that some people think the numbers presented there give a wrong picture of FreeBSD. Partly because not all benchmark numbers are presented in the most prominent page (as linked above), but only at a different place. This gives the impression that FreeBSD is inferior in this benchmark while it just puts the focus (for a reason, according to some people) on a different part of the benchmark (to be more specific, blogbench is doing disk reads and writes in parallel, FreeBSD gives higher priority to writes than to reads, FreeBSD 9 outperforms OLS 6.1 in the writes while OLS 6.1 shines with the reads, and only the reads are presented on the first page). Other complaints are that it is told that the default install was used (in this case UFS as the FS), when it was not (ZFS as the FS).

The author of the Phoronix article participated in parts of the discussion and asked for specific improvement suggestions. A FreeBSD committer seems to be already working to get some issues resolved. What I do not like personally, is that the article is not updated with a remark that some things presented do not reflect the reality and a retest is necessary.

As there was much talk in the thread but not much obvious activity from our side to resolve some issues, I started to improve the FreeBSD wiki page about benchmarking so that we are able to point to it in case someone wants to benchmark FreeBSD. Others already chimed in and improved some things too. It is far from perfect, some more eyes — and more importantly some more fingers which add content — are needed. Please go to the wiki page and try to help out (if you are afraid to write something in the wiki, please at least tell your suggestions on a FreeBSD mailinglist so that others can improve the wiki page).

What we need too, is a wiki page about FreeBSD tuning (a first step would be to take the man-page and convert it into a wiki page, then to improve it, and then to feed back the changes to the man-page while keeping the wiki page to be able to cross reference parts from the benchmarking page).

I already told about this in the thread about the Phoronix benchmark: everyone is welcome to improve the situation. Do not talk, write something. No matter if it is an improvement to the benchmarking page, tuning advise, or a tool which inspects the system and suggests some tuning. If you want to help in the wiki, create a FirstnameLastname account and ask a FreeBSD comitter for write access.

A while ago (IIRC we have to think in months or even years) there was some framework for automatic FreeBSD benchmarking. Unfortunately the author run out of time. The framework was able to install a FreeBSD system on a machine, run some specified benchmark (not much benchmarks where integrated), and then install another FreeBSD version to run the same benchmark, or to reinstall the same version to run another benchmark. IIRC there was also some DB behind which collected the results and maybe there was even some way to compare them. It would be nice if someone could get some time to talk with the author to get the framework and set it up somewhere, so that we have a controlled environment where we can do our own benchmarks in an automatic and repeatable fashion with several FreeBSD versions.

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