Re: [ANNOUNCE] kvm-14 release

[Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>]

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).

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.

Regards,

Anthony Liguori


-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys-and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV