FreeBSD

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Kernel config

Enable httpready / accf_http for use in Apache

Notes: Tested on FreeBSD 5.x, 6.x, and 7.x

From the man page of accf_http:
(used for Apache 2.2.x with "httpready" function call)

NAME
     accf_http -- buffer incoming connections until a certain complete HTTP
     requests arrive

SYNOPSIS
     options INET
     options ACCEPT_FILTER_HTTP
     kldload accf_http

To load it on boot - without the kernel option, put the following in /boot/loader.conf:

accf_data_load="YES" # Wait for data accept filter
accf_http_load="YES" # Wait for full HTTP request accept filter

NOTE: See the Apache page for configure options for Apache 2.2.x.

Device polling

Notes: Tested on FreeBSD 7.0-RELEASE-p6, 7.0-STABLE
Hints: DEVICE_POLLING, HZ=1000, ifconfig, polling

To enabled device polling you have to put the following 2 lines in your kernel config:

options DEVICE_POLLING
options HZ=1000

Now you can set polling for the devices needed (this only works on NICs/network interface cards so far).

The following line is an example of a valid entry in /etc/rc.conf:

ifconfig_em0="inet 10.0.0.110 netmask 255.255.255.0 polling"

Alternatively, you can set an OID in /boot/loader.conf:

kern.polling.enable=1

However - this OID is deprecated since Oct. 1st 2005 - but still works.

Controlling next boot

Notes: Tested on FreeBSD 7.0-RELEASE-p6
Hints: nextboot, nextboot_conf

Put the following in /boot/loader.conf

nextboot_enable="YES"

This will consequently set the boot environment from the file /boot/nextboot.conf

Once executed, this file (/boot/nextboot.conf) is deleted - so back it up, should you need it again.

This is perfect for testing kernel settings on remote sites, like:

hint.acpi.0.disabled="1"

That line can kill your box if certain drivers/devices do not load without ACPI. On the other hand, having ACPI enabled can make interrupt storms on your device IRQs - hence - you want to be able to fallback on a good known configuration should this fail to boot.

When things work like you want them to - put these settings into /boot/loader.conf to make them permanent. Some settings might also be worth putting into the actual kernel to gain performance.

How to get rid of interrupt storm (atapci0 and others)

Add the following to your kernel conf

options         KDB
options         KDB_UNATTENDED
options         DDB

Then re-compile, install, and reboot.

For some reason this made all my interrupt storms go away. My system is amd64 with a Microstar motherboard (MS-7368, V1.5B2). The controller is "IXP SB600 Serial ATA Controller".

Also see "Device_polling" in this article.

Disable Ctrl+Alt+Delete

Add this to your kernel

options SC_DISABLE_REBOOT

Binary update

Since FreeBSD 6.3 the tool freebsd-update has been bundled with FreeBSD.

When updating inside same version, say, from 7.0-RELEASE to 7.0-RELEASE-p7 all you need to do is:

freebsd-update fetch
freebsd-update install
shutdown -r now

This will investigate your system and identify what needs to be updated - including mergemaster issues. If more questions should appear - use common sense.

If you up to a new major version, you might need to do more, like freebsd-update upgrade. Read man page for details ;)

Recompile kernel

Notes: Tested on FreeBSD 7.0-RELEASE-p6

cd /usr/src
make buildkernel KERNCONF=MYKERNEL
make installkernel KERNCONF=MYKERNEL
shutdown -r now

Recompile world

First, update your source tree:

cd /root
cp /usr/share/examples/cvsup/stable-supfile ./
chmod 644 stable-supfile
vi stable-supfile # Find CHANGE_THIS and insert "cvsup.dk" or your preferred mirror.
csup stable-supfile

Next - recompile

cd /usr/src
script /root/buildworld.log # Use this to keep track of progress in another screen or after a crash
make -j16 buildworld
exit
script /root/buildkernel.log
make -j16 buildkernel   # KERNCONF=MYKERNEL for a custom kernel, see above.
exit
script /root/installkernel.log
make installkernel # KERNCONF=MYKERNEL for a custom kernel, see above.
shutdown -r now

If you have the option to do this in single user mode, do it!

# mount -a -t ufs

Then continue:

mergemaster -p
cd /usr/src
script /root/installworld.log
make installworld
mergemaster
shutdown -r now

PS: If running ezjails, please remember to update these, too!

How to mount ISO files virtually

Creation

mdconfig -a -t vnode -f image.iso -u 0
mount -t cd9660 /dev/md0 /mnt/cdimage

Destruction

mdconfig -d -u 0

How to create more PTYs

Need more ptys? Just run...

cd /dev
sh MAKEDEV pty1
sh MAKEDEV pty2
sh MAKEDEV pty3

...which will make you 128 ptys.

Also check "man MAKEDEV" for hints. Your "screen" will be much happier now ;)

PS: For FreeBSD 4.x you also need to recompile with "pseudo-device pty 128" or what number you fancy.

Need disks/partitions larger than 2 TB?

Disks are getting bigger and bigger, but bsdlabel (which sysinstall uses) does not like a partition larger than 2^32-1 sectors per disk.

To circumvent this "problem" you need to finish installing FreeBSD and run the gpt utility afterwards.

It goes something like this:

gpt create -f /dev/da0
gpt add -t ufs /dev/da0
newfs -n /dev/da0p1

Miscellaneous

source routing
multihomed isp

devfs

How to mount devfs in FreeBSD

mount -t devfs devfs /dev

procfs

How to show procfs in FreeBSD

mount -t procfs procfs /proc

How to hide procfs in FreeBSD

umount /proc

How to mirror your boot disk with geom

Read this article: http://www.freebsd.org/doc/en/books/handbook/geom-mirror.html

Make FreeBSD reboot on kernel panic

Put this into /etc/sysctl.conf

debug.debugger_on_panic=0

This will only work if you do not have KDB compiled into your kernel.

If you have KDB compiled into your kernel, also compile KDB_UNATTENDED into the kernel. This will make it reboot anyhow.