[virt-tools-list] virt-install: Getting initrd 'injection' to work...

Cole Robinson crobinso at redhat.com
Fri Oct 22 13:14:58 UTC 2010


On 10/22/2010 05:39 AM, Martin Ellis wrote:
> Two things I should have mentioned, to corroborate my patch:
> 
> On 21 October 2010 23:02, Martin Ellis wrote:
>> I had a look at the patch that introduced this feature [2], and noticed
>> that it was using cpio -c when repacking the initrd.
> 
> The -c option corresponds to the 'odc' format:
> http://info2html.sourceforge.net/cgi-bin/info2html-demo/info2html?(cpio.info.gz)Options
> 
> ... but the Linux doc I linked to says that only 'newc' and 'crc' are supported:
> http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6-stable.git;a=blob_plain;f=Documentation/early-userspace/buffer-format.txt;hb=HEAD
> 
> So if -c does work somewhere, it looks like it's relying on an
> undocumented feature.
> 
>> While I was looking, I also noticed that the initrd gets unpacked, and
>> then repacked again with the new files. Â A more efficient way to do
>> this is to simply append a new (compressed) cpio archive onto the end
>> of the original initrd.
> 
> Actually, efficiency isn't the only issue.  The current implementation
> won't work for a non-root user, because they won't be able to unpack
> the /dev directory in the initrd because it contains device nodes.
> This would also cause problems on filesystems mounted with nodev.
> 

Thanks for the patch, I'll give it a spin. What distro are you testing with?

- Cole




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