Re: [Xen-devel] Criteria for dom0_gnttab_start

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-10-21 at 17:24 +0530, Vijay Kilari wrote:
> Hi,
> 
>    What is the criteria for setting dom0_gnttab_start and size for a
> platform.

It simply needs to be an area of the IPA address space which is not
populated by anything else. Since dom0's MMIO space is mapped 1:1 with
the host PA address space it seems easiest/safest to find a hole in the
real physical space and use that.

If there is no such hole available then using the space occupied by some
device which is not passed to dom0 (e.g. is blacklisted, or used by Xen)
will suffice.

For an arm32 platform it should be below 4G.

Sizewise anything from 0x20000 should do.

Alignmentwise I suppose 2M aligned would be preferable for the guest,
but it's not mandatory.

Ian.

>  Till now I am using default gnttab map
> 
> Grant table range: 0x000000b0000000-0x000000b0020000
> 
> Regards
> Vijay



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