On Thu, Jan 11, 2018 at 01:05:01AM +0100, deloptes wrote:
> Greg Wooledge wrote:
>
> > Moreover, the simple zcat|cpio -i no longer works with stretch's initrd
> > images. They're in a different format, and you have to use
> > lsinitramfs or unmkinitramfs to see or extract their contents.
> >
> > On a jessie system, the zcat|cpio -i may still work (not sure about
> > backported kernels though).
>
> I just tested it on stretch
>
> file /boot/initrd.img-4.14.12eko4
> /boot/initrd.img-4.14.12eko4: gzip compressed data, last modified: Tue Jan
> 9 22:45:46 2018, from Unix
>
> $ zcat /boot/initrd.img-4.14.12eko4 | cpio -id
> 76825 blocks
>
> so if it is gzip format it works perfectly - what format do you mean?
Whatever "4.14.12eko4" is, it's not a stretch kernel image.
wooledg:~$ ls /boot
config-3.16.0-4-amd64 initrd.img-4.9.0-4-amd64 System.map-4.9.0-5-amd64
config-4.9.0-4-amd64 initrd.img-4.9.0-5-amd64 vmlinuz-3.16.0-4-amd64
config-4.9.0-5-amd64 lost+found vmlinuz-4.9.0-4-amd64
grub System.map-3.16.0-4-amd64 vmlinuz-4.9.0-5-amd64
initrd.img-3.16.0-4-amd64 System.map-4.9.0-4-amd64
wooledg:~$ zcat /boot/initrd.img-3.16.0-4-amd64 | cpio -itv | head -3
drwxr-xr-x 10 root root 0 Apr 10 2017 .
drwxr-xr-x 5 root root 0 Apr 10 2017 scripts
-rw-r--r-- 1 root root 9187 Apr 17 2016 scripts/functions
wooledg:~$ zcat /boot/initrd.img-4.9.0-5-amd64 | cpio -itv | head -3
gzip: /boot/initrd.img-4.9.0-5-amd64: not in gzip format
cpio: premature end of archive
wooledg:~$ lsinitramfs /boot/initrd.img-4.9.0-5-amd64 | head -3
kernel
kernel/x86
kernel/x86/microcode
wooledg:~$ file /boot/initrd.img-3.16.0-4-amd64
/boot/initrd.img-3.16.0-4-amd64: gzip compressed data, last modified: Mon Apr
10 14:03:50 2017, from Unix
wooledg:~$ file /boot/initrd.img-4.9.0-5-amd64
/boot/initrd.img-4.9.0-5-amd64: ASCII cpio archive (SVR4 with no CRC)
In fact, I believe the stretch initrd images are sequences of concatenated
cpio archives, some gzipped, some not, possibly with a NUL byte or
something between them.
wooledg:~$ cpio -itv < /boot/initrd.img-4.9.0-5-amd64
drwxr-xr-x 2 root root 0 Apr 9 2017 kernel
drwxr-xr-x 2 root root 0 Apr 9 2017 kernel/x86
drwxr-xr-x 2 root root 0 Apr 9 2017 kernel/x86/microcode
drwxr-xr-x 2 root root 0 Apr 9 2017
kernel/x86/microcode/.enuineIntel.align.0123456789abc
-rw-r--r-- 1 root root 98304 Apr 9 2017
kernel/x86/microcode/GenuineIntel.bin
194 blocks
Whereas, if you use lsinitramfs, you'll see far more content, from
the subsequent cpio archives in the image. Or, if you manually
string together multiple cpio commands:
wooledg:~$ { cpio -itv; echo XXXXXXX; zcat | cpio -itv | head -3; } <
/boot/initrd.img-4.9.0-5-amd64
drwxr-xr-x 2 root root 0 Apr 9 2017 kernel
drwxr-xr-x 2 root root 0 Apr 9 2017 kernel/x86
drwxr-xr-x 2 root root 0 Apr 9 2017 kernel/x86/microcode
drwxr-xr-x 2 root root 0 Apr 9 2017
kernel/x86/microcode/.enuineIntel.align.0123456789abc
-rw-r--r-- 1 root root 98304 Apr 9 2017
kernel/x86/microcode/GenuineIntel.bin
194 blocks
XXXXXXX
drwxr-xr-x 10 root root 0 Jan 5 08:00 .
drwxr-xr-x 5 root root 0 Jan 5 08:00 scripts
-rw-r--r-- 1 root root 9394 Mar 6 2017 scripts/functions
I don't actually know how many cpio archives are concatenated together
in that image. At least two, obviously, with the first uncompressed
and the second gzipped.
