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Re: [Qemu-devel] [RFC PATCH 1/4] qemu-options: Add -filefd command line
Re: [Qemu-devel] [RFC PATCH 1/4] qemu-options: Add -filefd command line option
Tue, 22 May 2012 15:26:45 +0100
On Tue, May 22, 2012 at 2:38 PM, Kevin Wolf <address@hidden> wrote:
> Am 22.05.2012 15:25, schrieb Corey Bryant:
>> On 05/21/2012 05:40 PM, Eric Blake wrote:
>>> On 05/21/2012 02:19 PM, Corey Bryant wrote:
>>>> This patch provides support for the -filefd command line option.
>>>> This option will allow passing of a filename and its corresponding
>>>> file descriptor to QEMU at exec time.
>>>> Signed-off-by: Corey Bryant<address@hidden>
>>>> +DEF("filefd", HAS_ARG, QEMU_OPTION_filefd,
>>>> + "-filefd file=<filename>,fd=<fd>\n"
>>> I take it that if filename contains ',', then we have to escape it on
>>> the command line? Is it worth passing fd first and file second by
>>> default, as a possible way to avoid the need for escaping, or does the
>>> option parser not care about ordering?
>> That's a good question. The options can be ordered either way so I
>> don't think we'll force fd to be specified first. I imagine this should
>> behave no differently than "-drive file=xyz,if=none,...". I ran a quick
>> test using -drive with a filename that had a comma, and (escaped or not)
>> it failed on the option parsing. So it looks like if you have a path
>> with a comma you're not going to have any luck.
> I think you can escape it, you'd have to use a double comma. But I'd
> rather not introduce more of this. It's another good reason for using
> /dev/fd/... instead of a translation table.
I'm not sure how this solves backing file descriptor passing? How
will QEMU know to use /dev/fd/10 for a backing file that is referenced
from /dev/fd/9 as "backing.img"? (There was discussion about
rewriting backing filenames but I think that solution is risky and we
should avoid it.)
[Qemu-devel] [RFC PATCH 4/4] Example -filefd and getfd_file server, Corey Bryant, 2012/05/21
[Qemu-devel] [RFC PATCH 3/4] block: Enable QEMU to retrieve passed fd before attempting open, Corey Bryant, 2012/05/21
[Qemu-devel] [RFC PATCH 2/4] qmp/hmp: Add getfd_file monitor command, Corey Bryant, 2012/05/21