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Re: [Xen-devel] [PATCH] xl, e820_host, PV passthrough: Fix guests crashing when memory == maxmem

On 24/05/13 15:55, Ian Campbell wrote:
On Fri, 2013-05-24 at 10:51 -0400, Konrad Rzeszutek Wilk wrote:
On Fri, May 24, 2013 at 02:58:24PM +0100, Ian Campbell wrote:
On Fri, 2013-05-24 at 09:36 -0400, Konrad Rzeszutek Wilk wrote:
The code had an obvious bug where it would assume that the balloon
amount would always be _something_ and add an E820_RAM entry at the
end of the E820 array. The added E820_RAM would contain the balloon amount
plus the delta of memory that had to be subtracted b/c of the various
E820 entries. That assumption is certainly true when maxmem != mem,
but if guest config has maxmem = memory that is incorrect (as balloon
value is zero). The end result is that the E820 that is constructed
is missing a swath of "delta" memory and in most cases ends up with
only one E820_RAM entry that is of 512MB size on many Intel systems.

Reported-by: Christian Holpert <christian@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Would you be OK putting this in Xen 4.3? It is only exposed if a user
  1) launches a PV guest
  2). Has in the guest config: pci=['blabla']\ne820_host=1
  3). Is not that freq used as only a couple of people seem to use it
TBH I was just going to commit it as an obvious bug fix in my next sweep
of my queue (probably on Tuesday at this rate...)

I guess George has until then to object ;-)

Sounds like a bug fix -- no objections. :-)


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