Stefan Hajnoczi wrote:
On Thu, Nov 17, 2011 at 5:18 AM, Supriya Kannery
<supri...@linux.vnet.ibm.com> wrote:
On 11/17/2011 01:36 AM, Stefan Hajnoczi wrote:
On Fri, Nov 11, 2011 at 6:48 AM, Supriya Kannery
<supri...@linux.vnet.ibm.com> wrote:
+ if ((hostcache = qemu_opt_get_bool(opts, "hostcache", -1)) !=
-1) {
This does not work. qemu_opt_get_bool() takes a bool default argument
and returns a bool. (bool)-1 == true. But (int)true == 1 and you
cannot expect it to ever equal -1.
Try this:
if (qemu_opt_get(opts, "hostcache")&&
!qemu_opt_get_bool(opts, "hostcache", false)) {
bdrv_flags |= BDRV_O_NOCACHE;
}
Stefan
Thanks! for pointing this.
Does the following look ok?
if ((hostcache = qemu_opt_get_bool(opts, "hostcache", 1) == 0) {
bdrv_flags |= BDRV_O_NOCACHE;
}
If either "hostcache" is not at all specified or it is specified
as "on", qemu_opt_get_bool will return 1, which can be ignored
as bdrv_flags is initialized to 0.
It depends on the overall way this should work. I think this captures
all the cases:
1. cache= and hostcache= may not be used together.
2. cache= sets bdrv_flags.
3. hostcache= may |= BDRV_O_NOCACHE.
4. No option defaults to cache=writethrough (bdrv_flags &= ~BDRV_O_CACHE_MASK).
The code you posted will work although I find it a bit weird how it
also includes case #4. IMO it's cleanest to just do case #3 by
testing whether or not the hostcache= option is set.
BTW, is there a check for case #1 in your patch series. I thought I
saw one earlier but now I can't find it.
Following is what I tried to accomplish:
1. cache= and hostcache= may be used together. Cache= will override hostcache=
if specified together
This condition can be retained till cache-xx can be completely replaced by combinations of separate
cmdline options defined for setting hostcache, flush, and WCE
[I think I can change the current implementation to have Cache=xx ORed with hostcache=yy if
they are specified together instead of just ignoring hostcache= ]
2. If only cache= specified sets bdrv_flags.
3. If only hostcache= specified, bdrv_flags |= BDRV_O_NOCACHE
4. No option defaults to cache=writethrough (bdrv_flags &= ~BDRV_O_CACHE_MASK).
So the check I had earlier for case #1 in your list, I changed that to
allow both the options to co-exist.
-thanks, Supriya
Stefan
