hw/audio/sb16: skip automatic zero-init of large array

The 'write_audio' method has a 4k byte array used for copying data
between the audio backend and device. Skip the automatic zero-init
of this array to eliminate the performance overhead in the I/O hot
path.

The 'tmpbuf' array will be fully initialized when reading data from
device memory.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20250610123709.835102-13-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/hw/audio/sb16.c b/hw/audio/sb16.c
index 19fd3b90205f7d139c55affae69141926db73aa8..bac64118fef918a961d83b4af74c8cd02430eae2 100644 (file)
--- a/hw/audio/sb16.c
+++ b/hw/audio/sb16.c
@@ -1181,7 +1181,7 @@ static int write_audio (SB16State *s, int nchan, int dma_pos,
     IsaDma *isa_dma = nchan == s->dma ? s->isa_dma : s->isa_hdma;
     IsaDmaClass *k = ISADMA_GET_CLASS(isa_dma);
     int temp, net;
-    uint8_t tmpbuf[4096];
+    QEMU_UNINITIALIZED uint8_t tmpbuf[4096];
 
     temp = len;
     net = 0;