Re: [Qemu-devel] [PATCH 1/2] nvram: Add TPM NVRAM implementation

[Kevin Wolf <kwolf@redhat.com>]

Am 05.06.2013 um 15:28 hat Corey Bryant geschrieben:
> >>+
> >>+    if (rwr->rc == 0) {
> >>+        rwr->rc = rwr->num_sectors;
> >>+        *rwr->blob_r = g_malloc(rwr->size);
> >>+        memcpy(*rwr->blob_r, buf, rwr->size);
> >
> >Use bdrv_pread()/bdrv_pwrite() for byte-granularity I/O instead of
> >duplicating the buffering yourself.
> >
> 
> Aren't bdrv_pread()/bdrv_pwrite() synchronous?  Wouldn't using them
> block the main QEMU thread?  That is why I switched to using the
> coroutine versions.

You need to call them from coroutine context to avoid that they invoke
their on coroutine on which they wait in this this while (!done)
{ qemu_aio_wait(); } loop that blocks everything. Called from coroutine
context, they do the Right Thing, though.

Kevin