Libguestfs - Dec 2016 - [PATCH] appliance: Disable EDD (edd=off) (RHBZ#1404287).

EDD (https://en.wikipedia.org/wiki/Enhanced_Disk_Drive) is a BIOS INT 13h
subcall for communicating the extended size of the boot disk over 8GB
to the OS.  Since libguestfs doesn't use a boot disk, and the
appliance disk is limited to 4GB, and we use virtio-scsi, this is all
useless.

EDD is also broken currently on RHEL 7.3, see:
https://bugzilla.redhat.com/show_bug.cgi?id=1404287

Also the EDD probing takes significant extra time (about 80ms on my
laptop), and using edd=off reduces this time although doesn't entirely
eliminate it.
---
 src/launch.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/launch.c b/src/launch.c
index 78bf46d..46d7ab9 100644
--- a/src/launch.c
+++ b/src/launch.c
@@ -363,6 +363,7 @@ guestfs_int_appliance_command_line (guestfs_h *g, const char
*appliance_dev,
       */
      " efi-rtc=noprobe"
 #endif
+     " edd=off"                 /* RHBZ#1404287 */
      " udevtimeout=6000"/* for slow systems (RHBZ#480319,
RHBZ#1096579) */
      " udev.event-timeout=6000" /* for newer udevd */
      " no_timer_check"  /* fix for RHBZ#502058 */
-- 
2.10.2

On Sunday, 18 December 2016 19:32:34 CET Richard W.M. Jones
wrote:
> EDD (https://en.wikipedia.org/wiki/Enhanced_Disk_Drive) is a BIOS INT 13h
> subcall for communicating the extended size of the boot disk over 8GB
> to the OS.  Since libguestfs doesn't use a boot disk, and the
> appliance disk is limited to 4GB, and we use virtio-scsi, this is all
> useless.
> 
> EDD is also broken currently on RHEL 7.3, see:
> https://bugzilla.redhat.com/show_bug.cgi?id=1404287
> 
> Also the EDD probing takes significant extra time (about 80ms on my
> laptop), and using edd=off reduces this time although doesn't entirely
> eliminate it.
> ---
LGTM.

Thanks,
-- 
Pino Toscano