Re: x86-64/kexec: crashkernel= without @xM suffix

[Simon Horman <horms@verge.net.au>]

On Fri, Apr 30, 2010 at 07:42:06AM +0100, Jan Beulich wrote:
> Was this ever tested by anyone? Has it ever worked with any Linux
> as secondary kernel? We're getting reports (and analysis confirms
> this) that the fact that Xen places the hole at the highest suitable
> address below 4G prevents kexec from working.
> 
> A possible fix is non-obvious, since there doesn't appear to be a
> hard boundary below which the hole must reside (especially for a
> 32-bit secondary kernel; for a 64-bit one it seems like any place
> below 2G would be acceptable).
> 
> Simply using Linux' strategy and allocating at the lowest possible
> address doesn't seem too nice a solution either, as we try to
> conserve on the use of low memory as much as possible almost
> everywhere else.

Hi Jan,

I don't recall specifically testing this combination.
I think that your suggestion of simply locating the hole as
low as possible is a good one though I fear there is
a gotcha in there somewhere.