Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom

[Paolo Bonzini]

On 02/07/2015 15:58, Laurent Vivier wrote:
> Since any /dev entry can be treated as a raw disk image, it is worth
> noting which devices can be accessed when and how. /dev/rdisk nodes are
> character-special devices, but are "raw" in the BSD sense and force
> block-aligned I/O. They are closer to the physical disk than the buffer
> cache. /dev/disk nodes, on the other hand, are buffered block-special
> devices and are used primarily by the kernel's filesystem code.

So the right thing to do would not be just to set need_alignment, but to
probe it like we do on Linux for BDRV_O_NO_CACHE.

I'm okay with doing the simple thing, but it needs a comment for non-BSDers.

Paolo