Re: Loading a 32 bit kernel from 64 bit grub-xen

[Phillip Susi]

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On 7/1/2014 12:18 PM, Andrey Borzenkov wrote:
> В Tue, 01 Jul 2014 12:06:08 -0400 Phillip Susi <address@hidden>
> пишет:
>
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>> I have been trying to fix grub to load a 32 bit kernel from the
>> 64 bit xen build.  After fixing up one or two minor issues with
>> the elf loader, I believe I now have it to the point where it
>> jumps correctly to the 32 bit kernel and it crashes there, since
>> it is 32 bit code still executing on a cpu in 64 bit mode.  The
>> question is how to return the cpu to 32 bit mode *under xen*?
>
>
> IIRC it was already discussed not long ago and it seems to be Xen
> limitation. You probably need to ask on xen-devel to be sure.
>
> Is it not more simple to use 32 bit grub with 32 bit kernel to
> start with?

The problem with that is that you have to know in advance which kernel
you are going to boot.  That makes configuring virtual hosts harder;
they just want one grub image they can use to chainload whatever the
guest wants to install in their domain.

Also there must be a way to do this otherwise a 64 bit kernel running
under xen wouldn't be able to execute a 32 bit binary.  I suppose I'll
Cc xen-devel.

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