[vbox-dev] vhd format not stable?
Frank.Mehnert at Sun.COM
Mon Jun 22 03:30:42 PDT 2009
On Friday 19 June 2009, Huihong Luo wrote:
> I tested it again, but it still crashed.
> I think I now found the cause, it's quite delicate, but you should be able
> to fix it right away.
> a8bd6ffd ff ff ff ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??
> The above is the bitmap when crashed. You can see the beginnig there are
> only 3 bytes are valid, the 4th byte will cause crash.
> But when you call
> ASMBitTest(const volatile void *pvBitmap, int32_t iBit)
> it will the 1st 4-byte int, thus caused the crash.
> The easiest fix is to allocate 8 byte length more for the bitmap, and zero
> fill them, that will definitely solve the issue. You can also change
> ASMBitTest method impl.
I think a better fix would be to ensure that ASMBitTest isn't called
with non-word-aligned memory addresses.
Dr.-Ing. Frank Mehnert Sun Microsystems, Inc. www.sun.com
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