Currently at startup if using cache=none on a filesystem lacking
O_DIRECT such as tmpfs, at startup QEMU prints
qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: file system may not support O_DIRECT
qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Could not open '/tmp/foo.img': Invalid argument
while at QMP level the hint is missing, so QEMU reports just
"error": {
"class": "GenericError",
"desc": "Could not open '/tmp/foo.img': Invalid argument"
}
which is close to useless for the end user trying to figure out what
they did wrong.
With this change at startup QEMU prints
qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Unable to open '/tmp/foo.img': filesystem does not support O_DIRECT
while at the QMP level QEMU reports a massively more informative
"error": {
"class": "GenericError",
"desc": "Unable to open '/tmp/foo.img': filesystem does not support O_DIRECT"
}
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
b18a24a9f8