Re: [PATCH] Included reserved memory regions in dom0 iommu mappings

[Keir Fraser <keir.fraser@eu.citrix.com>]

I'm not keen on Ross's patch anyway. I think if you have such a broken
system, the cmdline option should simply identity-map everything below 4GB,
unconditionally. Easy.

 -- Keir

On 26/02/2009 09:20, "Cui, Dexuan" <dexuan.cui@intel.com> wrote:

> The patch is useful when BIOS doesn’t report RMRR correctly; however the patch
> may not help in some situations.
> E.g., to work around a buggy BIOS, we may have to map such an E820 entry
> (XEN)  00000000cff0b000 - 00000000d0000000 (reserved).
> But if we use a xen parameter "mem=512m", or, if the host only has 512m
> memory, the variable 'max_page" is 512m/PAGE_SIZE, so even with the patch, the
> E820 entry would not be mapped, and Xen would still hang.
> 
> -- Dexuan
> 
> ________________________________________
> From: xen-devel-bounces@lists.xensource.com
> [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of Ross Philipson
> Sent: 2009年2月24日 4:01
> To: xen-devel@lists.xensource.com
> Subject: [Xen-devel] [PATCH] Included reserved memory regions in dom0 iommu
> mappings
> 
> This adds a boolean boot parameter to xen to allow reserved memory
> regions to be added to the iommu mappings for dom0. The parameter
> is "iommu_include_reserved" and is off by default. A warning is
> also traced when incorrect RMRR to system memory map values are
> detected. This is being added to address some incorrect BIOS's that
> do not report correctly the requied reserved memory ranges in
> the RMRRs. When this occurs it currently can cause early boot hangs
> and crashes.
> 
> Signed-off-by: Ross Philipson <ross.philipson@citrix.com>
> 
> Based on changeset 19238
> 
> Thanks
> Ross
> 
> 
> Ross Philipson
> Senior Software Engineer
> Citrix Systems, Inc
> 14 Crosby Drive
> Bedford, MA 01730
> 781-301-7949
> ross.philipson@citrix.com
>