[gentoo-soc] GSoC 2017: Atom Gentoo

[Huimin Zhang]

Hi,

I am interested in doing the Atom Gentoo project. I’ve looked through the
past versions of the project idea (micro Gentoo, Stateless Minimal Gentoo)
as well, and this is how I think things could work:

Atom Gentoo will have a build script that will generate a disk image,
complete with bootloader, to be cloned to disks for deployment. I suspect
BIOS is a lot more prevalent than UEFI for servers and virtualization so a
BIOS bootloader will be default. The default kernel config should be
tailored for virtualization.

Each installation of Atom Gentoo consists of two separate partitions for
the root filesystem. Only one will be in use at a time, and the other will
be used for upgrades. If an upgrade fails, the partially upgraded partition
should be reset to be a copy of the other partition. If an upgrade
succeeds, the unupgraded partition should copy the contents of the upgraded
partition. A stateful partition, possibly on an external device, can be
overlayed on top.

The logic for choosing which partition to boot and maintaining the two
partitions will be handled in the init of initramfs, and the functionality
of generating such an initramfs could be patched into genkernel.

For updates, Atom Gentoo can rsync from a server that was defined at build
time. By using rsync the updates are diff-only instead of fetching the full
image each time. This can run automatically in the background as a cronjob,
updating the root partition not currently in use.

I have some questions as well (is there more background on the project?):


Should Atom Gentoo be minimal to the point of excluding portage and not
being self-sufficient? Since Atom Gentoo will receive full atomic OS
updates, it doesn’t really need to update its own packages, and perhaps
package management as a whole can be offloaded? This makes a lot of sense
for mass deployment.

For building Atom Gentoo, should the starting point be one of the Gentoo
Stage 3 tarballs or even earlier? I am leaning towards “even earlier”,
which will be necessary if portage is cut out of Atom Gentoo.

Should Atom Gentoo use a specific stdlib? I think uClibc and musl fit this
project well, but I haven’t worked with them before.

Also, since I expect to be writing a lot of Bash, does Gentoo have its own
Bash style guide?


Best,
Min