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Re: [Xen-devel] [PATCH][HVM] HVM guest creation crashing with 1 MB of gu

To: Andre Przywara <andre.przywara@xxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH][HVM] HVM guest creation crashing with 1 MB of guest memory
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 04 May 2007 14:57:32 +0100
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On 4/5/07 14:47, "Andre Przywara" <andre.przywara@xxxxxxx> wrote:

> When an HVM guest is started and assigned exactly one Megabyte of RAM,
> XEN will crash due to a overflow in building the E820 map in line 90 of
> tools/libxc/xc_hvm_build.c:
> e820entry[nr_map].size = mem_size - 0x100000 - PAGE_SIZE * 3;
> If memsize is one MB, the result will be negative (and the member is
> unsigned). As I don't think this is worth fixing here, I simply
> increased the minimal required memory for guest from zero to one
> Megabyte. Could someone check the effect on paravirtualized guests?

Better to check and reject the memory size in xc_hvm_build() itself. I'll
make a patch to do this.

 -- Keir

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