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From: | Yongji Xie |
Subject: | Re: [Qemu-devel] [PATCH v2] vfio: Add support for mmapping sub-page MMIO BARs |
Date: | Tue, 4 Oct 2016 14:57:25 +0800 |
User-agent: | Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 |
On 2016/10/1 0:05, Paolo Bonzini wrote:
On 14/09/2016 00:55, Alex Williamson wrote:Paolo, as the reigning memory API expert, do you see any issues with this? Expanding the size of a container MemoryRegion and the contained mmap'd subregion and manipulating priorities so that we don't interfere with other MemoryRegions.I guess it's fine if you are okay with maintaining it. memory_region_set_size exists, might as well use it. :) What I'm worried about, is what happens if two such regions end up in the same guest page. Then the two priorities conflict.
Hi Paolo, I think I can answer this question. We would expand only one MemoryRegionwhich is page aligned and set its priority to zero if we have two region in the same guest page. Then the Memory Region with higher priority will overlap the expanded
part of page aligned one as if we didn't do the expanding. Thanks, Yongji
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