Re: [gentoo-project] Call for agenda items - Council meeting 2013-08-13

[William Hubbs <williamh@gentoo.org>]

[-- Attachment #1: Type: text/plain, Size: 2351 bytes --]

Council members,

As we all know, the way most linux distros support having /usr on a
separate file system from / is via an initramfs. One of these can be
built easily in gentoo with dracut, genkernel, or you can build one
manually [1].

In april 2012, the council voted that "separate /usr is a supported
configuration". According to a number of people at the time and since
then, the intent was to mandate that maintainers must support separate /usr
configurations without an initramfs.

This is the reason for the "sep-usr" use flag in busybox. This use flag
is a Gentoo-specific option that drops the busybox static binary in / with a
different name (ginit). Then you add init=/ginit on your kernel command
line with your boot loader configuration to run this binary which just
mounts / and /usr and starts the real init.

The council never really took a position on how separate /usr is
supported, so there are people who use separate /usr with neither of
these options and still expect this configuration to work.

There are significant advantages if we do not require maintainers to
support the use of separate /usr configurations without an early boot
mechanism like an initramfs or the sep-usr use flag on busybox.

First, we will not have to worry any more about making sure all of the
libraries needed by binaries in /{bin,sbin} are in /lib*. Also, we will
not have to be concerned about programs on / trying to read data from
/usr/share in early boot.

Also, the support for separate /usr setups without any kind of early
boot mechanism is going to become more complex over time due to the
evolution of modern software. Our QA lead has some blog posts on the
separate /usr issue and the boot process which discuss these issues in
more detail [2] [3]. Another thing to consider is FHS 3 [4]. The division
between / and /usr is becoming blurred because any combination of
actual directories and symlinks are allowed in /.

Because of this information, I propose that we vote not to
require maintainers to support separate /usr configurations without an
initramfs or some other early boot mechanism.

William

[1] http://www.gentoo.org/doc/en/initramfs-guide.xml
[2] https://blog.flameeyes.eu/2012/12/my-take-on-the-separate-usr-issue
[3] https://blog.flameeyes.eu/2013/01/the-boot-process
[4] http://www.linuxbase.org/betaspecs/fhs/fhs.html

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 198 bytes --]