Re: Size of initrd
On Sun 22 Nov 2020 at 23:46:54 (-0500), Stefan Monnier wrote:
> >> I have two machines with very similar setups: both running Debian i386
> >> testing, they actually come from the same install done years ago
> >> and were cloned at some point in time.
> >>
> >> One of the has /boot/initrd.img files that take about 15MB while the
> >> other has /boot/initrd.img files that take about 30MB (in both cases,
> >> they are compressed with `lzma`).
> >>
> >> Any idea what this difference could come from (or how I could try and
> >> track it down) and how I could fix the size to be more like 15MB?
> >
> > The initramfs is a compressed cpio archive (of the initial file
> > system at boot time).
>
> Duh! Indeed, even `file` tells me that.
> It turns out that the bigger one says it's an "ASCII cpio archive",
> whereas the smaller one says it's an LZMA compressed file.
>
> So apparently the issue is that while I configured "lzma" on both
> machines in /etc/initramfs, one of the two machines maybe doesn't have
> `lzma` installed?
>
> > You can inspect it like so:
> >
> > gunzip < /boot/initrd.img-4.19.0-10-amd64 | cpio -it | less
>
> The "smaller" archive (the one that got compressed) gives me the kind of
> listing I expected (except I see a lot of X11-related crap in there, it
> looks like some kind of "boot splash screen" code got in there even
> I thought I had all that disabled),
> but oddly the "bigger" archive gives me a much smaller list:
>
> % cpio -vt < yuca-initrd.img-5.9.0-2-686-pae
> drwxr-xr-x 2 root root 0 Aug 20 08:00 kernel
> drwxr-xr-x 2 root root 0 Aug 20 08:00 kernel/x86
> drwxr-xr-x 2 root root 0 Aug 20 08:00 kernel/x86/microcode
> drwxr-xr-x 2 root root 0 Aug 20 08:00 kernel/x86/microcode/.enuineIntel.align.0123456789abc
> -rw-r--r-- 1 root root 3692544 Aug 20 08:00 kernel/x86/microcode/GenuineIntel.bin
> 7214 blocs
> % l yuca-initrd.img-5.9.0-2-686-pae
> -rw-r--r-- 1 monnier users 24421797 nov 21 14:51 yuca-initrd.img-5.9.0-2-686-pae
> %
>
> How come the archive weighs in at 24MB when it doesn't even contain 4MB
> of data?
Use unmkinitramfs. It appears you've only looked at the first archive,
the early one, which gets the kernel into shape. The second, main one
is the big one.
Cheers,
David.
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