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Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom |
Date: |
Wed, 8 Jul 2015 12:31:25 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 02.07.2015 um 16:18 hat Laurent Vivier geschrieben:
>
>
> On 02/07/2015 16:03, Paolo Bonzini wrote:
> >
> >
> > 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.
>
> So, what we have to do, in our case, for MacOS X cdrom, is something like:
>
> ... GetBSDPath ...
> ...
> if (flags & BDRV_O_NOCACHE) {
> strcat(bsdPath, "r");
> }
> ...
I would avoid such magic. What we could do is rejecting /dev/rdisk nodes
without BDRV_O_NOCACHE.
Kevin
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, (continued)
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Stefan Hajnoczi, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Laurent Vivier, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Paolo Bonzini, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Laurent Vivier, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Paolo Bonzini, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Laurent Vivier, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Paolo Bonzini, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Laurent Vivier, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Programmingkid, 2015/07/02
- Re: [Qemu-devel] [PATCH v2] raw-posix.c: remove raw device access for cdrom, Programmingkid, 2015/07/02
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom,
Kevin Wolf <=
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Laurent Vivier, 2015/07/08
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Kevin Wolf, 2015/07/08
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Programmingkid, 2015/07/08
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Kevin Wolf, 2015/07/08
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Programmingkid, 2015/07/08
- Re: [Qemu-devel] [PATCH] raw-posix.c: remove raw device access for cdrom, Laurent Vivier, 2015/07/08
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