VFIO currently allocates it's own dynamic chardev range, reserving the
first minor for the control part of the interface (/dev/vfio/vfio) and
the remainder for VFIO groups (/dev/vfio/$GROUP). This works, but it
doesn't support auto loading. For instance when libvirt checks for
VFIO support it looks for /dev/vfio/vfio, which currently doesn't
exist unless the vfio module is loaded. By converting the control
device to a misc driver and reserving a static minor, we can enable
auto loading.
Reserving the minor is a prerequist to that conversion. Minor 196
is unused by anything currently in the kernel.
Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Alex Williamson <alex.william...@redhat.com>
---
v2: Plea for ack edition
As Alan suspected, there's been no response from dev...@lanana.org,
so there's probably nobody monitoring it anymore. I've done due
diligence looking at all the callers of misc_register() in linux-next
and cannot find any conflicts with minor 196. If anyone wants to toss
me an ack or sign-off I'll be happy to bring this in through my vfio
tree, otherwise I'd appreciate if someone wants to take it directly.
Thanks!
Documentation/devices.txt | 1 +
include/linux/miscdevice.h | 1 +
2 files changed, 2 insertions(+)
diff --git a/Documentation/devices.txt b/Documentation/devices.txt
index 80b7241..10378cc 100644
--- a/Documentation/devices.txt
+++ b/Documentation/devices.txt
@@ -409,6 +409,7 @@ Your cooperation is appreciated.
193 = /dev/d7s SPARC 7-segment display
194 = /dev/zkshim Zero-Knowledge network shim control
195 = /dev/elographics/e2201 Elographics touchscreen
E271-2201
+ 196 = /dev/vfio/vfio VFIO userspace driver interface
198 = /dev/sexec Signed executable interface
199 = /dev/scanners/cuecat :CueCat barcode scanner
200 = /dev/net/tun TAP/TUN network device
diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h
index f7eaf2d..3737f72 100644
--- a/include/linux/miscdevice.h
+++ b/include/linux/miscdevice.h
@@ -30,6 +30,7 @@
#define STORE_QUEUE_MINOR 155
#define I2O_MINOR 166
#define MICROCODE_MINOR 184
+#define VFIO_MINOR 196
#define TUN_MINOR 200
#define CUSE_MINOR 203
#define MWAVE_MINOR 219 /* ACP/Mwave Modem */
--
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