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Re: [Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device
From: |
Gabriel L. Somlo |
Subject: |
Re: [Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device |
Date: |
Sat, 19 Dec 2015 10:10:07 -0500 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
Hi Pavel,
On Sat, Dec 19, 2015 at 10:12:28AM +0100, Pavel Machek wrote:
> On Thu 2015-12-17 11:09:23, Gabriel L. Somlo wrote:
> > ping ?
> >
> > Also, for the corresponding patch set on the QEMU end of things,
> > ping on http://thread.gmane.org/gmane.comp.emulators.qemu/376321
>
> I guess missing information is why such access is a good
> idea. Debugging?
Debugging did come up in earlier threads as well. However, personally,
I am interested in a mechanism for the host to pass information to the
guest in a way that's both
- asynchronous: i.e., host doesn't need to wait for guest to
be ready to accept data (e.g. by first starting an agent)
- out-of-band: don't commandeer guest elements normally visible
and available to guest *users* (e.g. kernel command line,
mount a floppy/cdrom image, etc).
QEMU now allows arbitrary fw_cfg blobs to be added via the command
line, so it would be nice to make it easy to access them from the
guest OS -- and what's nicer and easier than:
cat /sys/firmware/qemu-fw-cfg/.../some-blob-name/raw
Thanks,
--Gabriel
> > On Fri, Dec 04, 2015 at 10:29:02AM -0500, Gabriel L. Somlo wrote:
> > > Allow access to QEMU firmware blobs, passed into the guest VM via
> > > the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
> > > size, and fw_cfg key), as well as the raw binary blob data may be
> > > accessed.
> > >
> > > The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
> > > selected based on overall similarity to the type of information
> > > exposed under /sys/firmware/dmi/entries/...
>
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures)
> http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
- [Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device, Gabriel L. Somlo, 2015/12/04
- [Qemu-devel] [PATCH v6 2/4] kobject: export kset_find_obj() for module use, Gabriel L. Somlo, 2015/12/04
- [Qemu-devel] [PATCH v6 3/4] firmware: create directory hierarchy for sysfs fw_cfg entries, Gabriel L. Somlo, 2015/12/04
- [Qemu-devel] [PATCH v6 4/4] devicetree: update documentation for fw_cfg ARM bindings, Gabriel L. Somlo, 2015/12/04
- [Qemu-devel] [PATCH v6 1/4] firmware: introduce sysfs driver for QEMU's fw_cfg device, Gabriel L. Somlo, 2015/12/04
- Re: [Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device, Gabriel L. Somlo, 2015/12/17