Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

[Eric W. Biederman]

"H. Peter Anvin" <hpa@xxxxxxxxx> writes:

> Jeremy Fitzhardinge wrote:
>> Eric W. Biederman wrote:
>>> All it does is set a flag that tells a bootloader.
>>> "Hey. I can run when loaded a non-default address, and this is what
>>>  you have to align me to."
>>>
>>> All relocation processing happens in the kernel itself.
>>>   
>> 
>> Is it possible to decompress and extract the kernel image from the
>> bzImage without executing it?  Ie, is there enough information to find
>> the compressed data part of the bzImage by inspection?
>> 
>> At some point we'll need to change the Xen domain builder to handle
>> bzImage files, and it would be best if we didn't need to run them.
>> 
>
> Probabilistically, you might be able to (search for a gzip header), but
> it is *definitely* not guaranteed by protocol.

I suspect the issue isn't so much skipping the decompression
but either getting at the Xen ELF notes or bypassing privileged instructions.


Eric
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