Re: [Xen-devel] [PATCH] Fix write parameter masking for 32-bit guests.

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

Okay, see c/s 15053.

 Thanks,
 Keir

On 13/5/07 09:47, "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:

> Well, the method in the previous mail may be a little complex -- I think the
> simplest way is:
> 
> -    if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) && (req->size !=
> sizeof(req->data)))
> +    if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) && (req->size !=
> sizeof(long)))
> 
> Since sizeof(long) = 4 in 32-bit platform, and  = 8 in 64-bit platform, the
> code here can work properly in 32/64-bit platforms.
> 
> -- Dexuan
> 
> 
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Cui, Dexuan
> Sent: 2007年5月13日 15:49
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Keir Fraser
> Subject: [Xen-devel] [PATCH] Fix write parameter masking for 32-bit guests.
> 
> Changeset 15046:e527b4ff1948 breaks 32-bit HVM guest: when req->size is
> 4, "1UL << 32" returns 1 in IA32 system, so the mask becomes 0 wrongly.
> The attached patch fixes this by using 64-bit left-shift.
> 
> Signed-off-by: Dexuan Cui <dexuan.cui@xxxxxxxxx>
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel



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