Jan Beulich
2010-Apr-30 06:42 UTC
[Xen-devel] x86-64/kexec: crashkernel= without @xM suffix
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. Thanks, Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Simon Horman
2010-May-02 02:21 UTC
Re: [Xen-devel] x86-64/kexec: crashkernel= without @xM suffix
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. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel