Re: [Qemu-devel] [PATCH] ide_dma_cancel will result in partial DMA transfer

[Ian Jackson]

Andrea Arcangeli writes ("[Qemu-devel] [PATCH] ide_dma_cancel will result in 
partial DMA transfer"):
> From: Andrea Arcangeli <address@hidden>
> 
> The reason for not actually canceling the I/O is because with
> virtualization and lots of VM running, a guest fs may mistake a
> overload of the host, as an IDE timeout. So rather than canceling the
> I/O, it's safer to wait I/O completion and simulate that the I/O has
> completed just before the io cancellation was requested by the
> guest. [...]

I haven't tested this patch, but the reasoning seems sound.  The only
downside would seem to be that this may make the cancellation IO port
write take a rather long time while we wait for a flush, so a guest
that did it a lot might have performance problems.

Acked-By: Ian Jackson <address@hidden>

Ian.