Messages in this thread | | | From | "Alexander van Heukelum" <> | Subject | Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit | Date | Fri, 29 Feb 2008 19:56:52 +0100 |
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On Fri, 29 Feb 2008 10:44:36 -0800, "H. Peter Anvin" <hpa@zytor.com> said: > Alexander van Heukelum wrote: > > > > My first guess is that the BIOS data area is completely non-existent for > > Xen. > > Is it guaranteed that the memory is zeroed out on boot? In that case we > > can > > special-case it easily: > > > > change: > > /* Paranoia: should never happen, but... */ > > if (lowmem >= 0x100000) > > lowmem = 0xa0000; > > > > into: > > /* Strange case, like Xen ;) */ > > if (lowmem == 0 || lowmem >= 0x100000) > > lowmem = 0x9f000; > > > > Can you test that? > > > > The EBDA is optional anyway; I presume it should have a zero pointer if > it isn't present.
Correct, but the value that indicates the size of the conventional memory area must be set. At least on any real hardware. My guess is that both values read as 0 on Xen, which causes 0-0x100000 to be reserved. If that is always the case the workaround is fine, I think.
Alexander
> -hpa -- Alexander van Heukelum heukelum@fastmail.fm
-- http://www.fastmail.fm - mmm... Fastmail...
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