Re: [Qemu-devel] [PATCH] Disable O_DIRECT for physical CDROM/DVD drives

[Natalia Portillo]

El 20/07/2010, a las 16:17, address@hidden escribió:

> From: Jes Sorensen <address@hidden>
> 
> O_DIRECT (cache=none) requires sector alignment, however the physical
> sector size of CDROM/DVD drives is 2048, as opposed to most disk
> devices which use 512. QEMU is hard coding 512 all over the place, so
> allowing O_DIRECT for CDROM/DVD devices does not work.

What about if the device is a 4096 byte/sector hard disk, a 512 byte/sector 
CD-ROM (IRIX ones), a 2048 byte/sector magnetooptical?

We should get rid of that hard codes and use real values.

> Signed-off-by: Jes Sorensen <address@hidden>
> ---
> block/raw-posix.c |    5 +++++
> 1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 291699f..0ea79b6 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -1139,6 +1139,11 @@ static int cdrom_open(BlockDriverState *bs, const char 
> *filename, int flags)
>     BDRVRawState *s = bs->opaque;
> 
>     s->type = FTYPE_CD;
> +    if (flags & BDRV_O_NOCACHE) {
> +        fprintf(stderr, "Disabling unsupported O_DIRECT (cache=none) for "
> +                "CDROM/DVD device (%s)\n", filename);
> +        flags &= ~BDRV_O_NOCACHE;
> +    }
> 
>     /* open will not fail even if no CD is inserted, so add O_NONBLOCK */
>     return raw_open_common(bs, filename, flags, O_NONBLOCK);
> -- 
> 1.7.1.1
> 
>