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Re: [Qemu-devel] [RFC PATCH] mmio-exec: Make device return MemoryRegion
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC PATCH] mmio-exec: Make device return MemoryRegion rather than host pointer |
Date: |
Mon, 30 Apr 2018 12:46:45 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 26/04/2018 17:09, Peter Maydell wrote:
>
> QUESTIONS:
> * do we really need to postpone things from
> memory_region_invalidate_mmio_ptr() to
> memory_region_do_invalidate_mmio_ptr(), given that the deletion of
> the memory region and ramblock is RCU-deferred anyway?
> * should we add the subregion at elevated prio so it definitely hits
> first? I've left it the way the existing code does for the
> moment...
> * is there any way to avoid the weird self-owning MemoryRegion
> and corresponding need to pass a NULL name pointer?
There would be, but the comment here says why it'd be an issue:
/* Memory regions without an owner are supposed to never go away;
* we do not ref/unref them because it slows down DMA sensibly.
*/
if (mr && mr->owner) {
object_ref(mr->owner);
}
though perhaps we can remove that other hack in 2.13, which will have
MemoryRegionCache again.
Paolo