raw-posix: warn about BDRV_O_NATIVE_AIO if libaio is unavailable

raw-posix.c silently ignores BDRV_O_NATIVE_AIO if libaio is unavailable.
It is confusing when aio=native performance is identical to aio=threads
because the binary was accidentally built without libaio.

Print a deprecation warning if -drive aio=native is used with a binary
that does not support libaio.  There are probably users using aio=native
who would be inconvenienced if QEMU suddenly refused to start their
guests.  In the future this will become an error.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2015-07-23 13:48:34 +01:00 committed by Kevin Wolf
parent 15489c769b
commit 1501ecc1d8

View File

@ -519,7 +519,16 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
"future QEMU versions.\n",
bs->filename);
}
#endif
#else
if (bdrv_flags & BDRV_O_NATIVE_AIO) {
error_printf("WARNING: aio=native was specified for '%s', but "
"is not supported in this build. Falling back to "
"aio=threads.\n"
" This will become an error condition in "
"future QEMU versions.\n",
bs->filename);
}
#endif /* !defined(CONFIG_LINUX_AIO) */
s->has_discard = true;
s->has_write_zeroes = true;