Re: [Xen-devel] [VTD][PATCH] Use bitmap to solve domain-id limitation issue

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

Why must a list be walked every time you want to translate domid->iommu_id?
Wouldn't you be better to store it in struct hvm_iommu?

Under what lock is the list of domid/iommu_id mappings protected? Under what
lock is the allocation bitmap protected (if necessary)?

This patch is definitely in the right direction, I just think it's not fully
baked yet...

 -- Keir

On 29/11/07 13:33, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:

> The Capability register reports the domain-id width supported by
> hardware. For implementations supporting less than 16-bit domainids,
> unused bits of domain identifier field(87:72) in Context entry are
> treated as reserved by hardware. For example, for an implementation
> supporting 4-bit domain-ids, bits 87:76 of this field are treated as
> reserved. 16 is a small number, overflow is easy to happen. What's more,
> context-entries programmed with the same domain identifier must always
> reference the same address translation structure (through the ASR
> field). So Dom16 will conflict with Dom0, and device assignment fails.
> 
> This patch implements a domaid id bitmap to solve above issue.
> 
> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
> _______________________________________________
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> http://lists.xensource.com/xen-devel



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