Gentoo Archives: gentoo-dev

From: William Hubbs <williamh@g.o>
To: gentoo-dev@l.g.o
Subject: Re: [gentoo-dev] Re: rfc: locations of binaries and separate /usr
Date: Sun, 01 Jan 2012 18:37:24
Message-Id: 20120101183259.GB11860@linux1
In Reply to: [gentoo-dev] Re: rfc: locations of binaries and separate /usr by Duncan <>
On Sun, Jan 01, 2012 at 09:23:11AM +0000, Duncan wrote:
> Gentoo has historically been both "light patch", with a policy of staying > close to upstream if possible, and "customizer's choice", allowing users > far more flexibility than most distros. Keeping both goals in mind, > migrating with upstream is ultimately the only viable alternative for a > whole host of reasons including both staying close to upstream and simple > manpower resource issues.
> That said, we can continue to try to support a separate /usr as long as > possible, while switching new installs to the new way and changing the > handbook to document it, preferably as soon as possible.
In this situation, I don't know how we will be able to support both ways because there is more involved than just where things are installed. Udev 175 is currently masked, because the way it operates has changed enough that it doesn't work correctly if it starts before /usr is mounted, and the failures you find will be very difficult to track down. So, udev isn't only changing where it is installed, but how it runs. Supporting a separate /usr without an initramfs will require one of two things. One possibility is a customization to openrc, which we have been looking at, that would be able to run fsck on /usr and mount /usr all before udev starts. The drawback here is this will only work for openrc users. Another possibility is a script that would run as the init= parameter to the kernel, which would fsck /usr and mount /usr then start the real init process. This would be more generic and would be able to run regardless of whether you are using sysvinit/openrc. Here is the big problem with both of these solutions as I see them. They depend on several pieces of software remaining on the root filesystem, and if/when this software is migrated, we will be back to having this discussion again.
> Further, as > previously discussed, a near-static bare-minimal initramfs that can be > configured and forgotten about for long periods over many kernel upgrades > should make the switch as painless as possible at least for "simple" bare- > partition installations.
I want to look at dracut and see if there is a way to configure it to create a minimal initramfs like you are suggesting, because, if there is we don't need to re-invent the wheel. I don't think your portage feature/use flag suggestion is a good idea, because, right now most of this is about where things are installed, but, eventually we might have to start actually patching software to make it work if it is installed on / instead of /usr, and there is no way to know how much patching we would have to do. What are your thoughts? William


Subject Author
Re: [gentoo-dev] Re: rfc: locations of binaries and separate /usr William Hubbs <williamh@g.o>