Re: [Qemu-devel] Re: [PATCH 2/3] Move aio implementation out of raw block driver

[Anthony Liguori]

Gerd Hoffmann wrote:
> Ryan Harper wrote:
>   
> > > So what happens if !defined(CONFIG_AIO)?  By my reading of the code, 
> > > aio_drv will be NULL and this will SEGV.
> > >       
> > raw_aio_read/write/cancel aren't included in the bdrv structure unless
> > CONFIG_AIO is defined.  Rather in bdrv_register, the aio emulation
> > functions are used instead.
> >     
>
> How about providing a aio interface implementation which simply uses
> read/write syscalls (thereby not being really async obviously)?  Then
> use that as fallback instead of aio emulation?  And also drop CONFIG_AIO
> then?
>   

Yeah, this is basically what block-raw-posix does today.  I was thinking 
the same thing.  I was also thinking that you could do an aio 
implementation for win32 and possibly reunify block-raw-posix and 
block-raw-linux.

But before going down this route, I want to see if linux-aio is really 
the right tool for the job.

Regards,

Anthony Liguori

> cheers,
>   Gerd
>