Re: [ANNOUNCE] kvm-14 release

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Anthony Liguori wrote:
> Avi Kivity wrote:
>> Laurent Vivier wrote:
>>> There are remaining issues : libposix-aio uses kernel AIO, so files 
>>> must be
>>> opened using O_DIRECT and buffers must be aligned. libposix-aio is 
>>> able to
>>> manage other cases but this has a performance cost.
>>>
>>>   
>>
>> Because the guest is also doing dma, the buffers are expected to be 
>> aligned (it might be different if using pio, but unlikely).
>
> The IDE emulation always uses a temporary buffer.  This is partially 
> because you cannot always rely on being able to use an offset on 
> phys_ram_base (when doing user only emulation).

Why is that?


>
> We can pretty easily patch this code though to use the DMA address 
> directly instead of the temporary buffer in the non PIO case.  We 
> still have to define a raw_pread() that is capable of emulating sector 
> alignment though since Linux will use PIO at first.

Sure.  It seems worthwhile for mainline qemu too.


-- 
error compiling committee.c: too many arguments to function


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