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Re: [Qemu-devel] Re: block: format vs. protocol, and how they stack
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] Re: block: format vs. protocol, and how they stack |
Date: |
Tue, 22 Jun 2010 17:46:06 +0100 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Markus Armbruster wrote:
> A possible reason why we currently expose format and protocol at the
> user interface is to avoid stacking there.
Pragmatic solution?: A few generic flags in each stacking module
("format/protocol/transport"), which govern which other modules are
allowed to stack on top or underneath.
For example, vvfat may provide a blockdev-like abstraction, along with
flags STACK_ABOVE_ONLY_RAW | STACK_BELOW_ONLY_DIRECTORY, which means
"raw" and "blkdebug" are allowed above (of course ;-) but other things
like the image formats shouldn't be. And below, it can't stack on a
blockdev-like abstraction, but needs a directory and uses filesystem
operations on it - the thing that Plan9fs needs.
Btw, I think we expose "format" because "virtual disk image file
format" is a useful and meaningful concept to users. When someone
needs to use a .VMDK file, they know it as a "VMDK format file", not
"I must use the VMDK protocol with this file".
-- Jamie
- [Qemu-devel] block: format vs. protocol, and how they stack, Markus Armbruster, 2010/06/18
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Avi Kivity, 2010/06/20
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Markus Armbruster, 2010/06/21
- Re: [Qemu-devel] Re: block: format vs. protocol, and how they stack,
Jamie Lokier <=
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Kevin Wolf, 2010/06/21
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Anthony Liguori, 2010/06/21
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Kevin Wolf, 2010/06/21
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Anthony Liguori, 2010/06/21
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Kevin Wolf, 2010/06/21
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Anthony Liguori, 2010/06/21
- [Qemu-devel] Re: block: format vs. protocol, and how they stack, Anthony Liguori, 2010/06/21
- Re: [Qemu-devel] Re: block: format vs. protocol, and how they stack, Christoph Hellwig, 2010/06/21
- Re: [Qemu-devel] Re: block: format vs. protocol, and how they stack, Paul Brook, 2010/06/21
- Re: [Qemu-devel] Re: block: format vs. protocol, and how they stack, Anthony Liguori, 2010/06/21