Re: [PATCHv11 3/9] kexec: add infrastructure for handling kexec images

[David Vrabel <david.vrabel@citrix.com>]

On 15/11/13 14:35, Jan Beulich wrote:
>>>> On 08.11.13 at 13:50, David Vrabel <david.vrabel@citrix.com> wrote:
>> Add the code needed to handle and load kexec images into Xen memory or
>> into the crash region.  This is needed for the new KEXEC_CMD_load and
>> KEXEC_CMD_unload hypercall sub-ops.
> 
> I know it's late in the game, but just now I started getting the
> impression that this introduced a new limitation that needs to
> be taken into consideration elsewhere: With the old
> implementation it was the kernel's responsibility to write to
> the reserved space or, where Xen needed to touch the space,
> it did so via fixmap entries. Hence there was no need for the
> area to have corresponding struct page_info.
> 
> The new code, however, appears to make assumptions that
> the memory used here is part of the range covered by the
> frame table, and hence setup.c's determination of the base
> address would need to be adjusted accordingly. (I realize
> that this only matters on systems having more RAM than the
> hypervisor can make use of.)

The relocation code wrote the image into the crash region, not the
kernel, but I take your point.

Is this a real problem or just a theoretical one for now? I don't think
it's unreasonable to require the crash region to be within the frame table.

David