Re: [Xen-devel] [PATCH 1/2][VTD] pci mmconfig support to be usedfor ATS

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 20.11.08 21:20 >>>
>On 20/11/08 20:10, "Kay, Allen M" <allen.m.kay@xxxxxxxxx> wrote:
>
>>> If this is x86-64 only anyway, why do you need to use fixmap
>>> space for this (and limit things arbitrarily to 4 segments)
>>> rather than using a 256Mb block from one of the unused virtual
>>> address regions in hypervisor space?
>> 
>> Can you point me how to use unused virtual address region to do ioremap
>> without using fixmap?  Is there a existing code that is already doing this?
>
>Pick yourself a nice piece of virtual address space (see the layout in
>include/asm-x86/config.h -- 0xffff840000000000 would be fine) and then use
>map_pages_to_xen().

While it can be adjusted later anyway, I'd suggest not using a part of this
largest available range - sooner or later we'll want to use this to extend
the 1:1 mapping to 4Tb. Instead, I'd pick another 1Gb range out of the
461Gb reserved region.

Jan


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