Bryan Kadzban wrote:
Tim Tassonis wrote:
On 29.08.2015 18:00, Bruce Dubbs wrote:
1. "Early system boot is the province of initrd." does not have to be
true. initrd is for commercial distros. We show in LFS that an initrd
is not needed and is quite a bit more complicated than booting without.
I would say that even a lot of distros could do away with the initrd
most of the time, if they would would provide two kernels:
- One fully modular, as is the case now
- One with the sata, ext4 and maybe md drivers compiled in.
I should note that that will only work if your rootfs is in a "normal"
partition (BIOS style partitions definitely work; I think UEFI might work now
too but am not 100% sure on that), with only an ext4 layer between the
partition table and the filesystem.
You mention md -- I'm not sure if that will autoassemble these days in the
kernel, or if it still requires userspace to run mdadm. Assuming it can
autoassemble, there's also LVM, which can't (it's self-describing but requires
that someone run "vgchange -a y").
See http://www.linuxfromscratch.org/lfs/view/stable/scripts/apds05.html
(/etc/rc.d/init.d/udev)
There's also encrypted rootfs, which can't
(it requires someone run cryptsetup, either in LUKS mode asking for a
passphrase for one of the slots, or in raw mode, where you just have to give
it the raw key).
Now, granted, if none of these is in use, then an initramfs-less boot is a lot
simpler, and I would recommend it wherever possible. But there are a few
cases where it's not possible.
...NFS root is another, I suspect. Not sure if the kernel flags for NFS root
are still present or not.
(Note also that GRUB2's support for these is not exactly relevant here, as
GRUB doesn't mount the rootfs, it only loads up the kernel and initramfs image
files. So the state of /boot is relevant to the GRUB support, but not the
state of the rootfs. Unless those are the same; then both have to support the
setup being used.)
Yes, see
http://www.linuxfromscratch.org/blfs/view/svn/postlfs/initramfs.html,
fourth paragraph.
-- Bruce
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