[Qemu-devel] [PATCH, RFC 0/4] allow guest control of the volatile write cache

[Christoph Hellwig]

This series adds support for the guest to control the volatile write
cache setting on disks exported by qemu for ide and virtio.
For ide it just wires up the existing SETFEATURES calls, and for virtio
it adds a new writeable config space field.  SCSI is not supported at
this point, as the convoluted callback mess in the SCSI stack doesn't
allow commands except for plain WRITEs to read data from guest memory.

The backend is based on the code that Prerna posted a while ago,
and not Stefan's /proc based variant.  I'm open to either one, but
the problem with the /proc based one is that it's Linux-specific.