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hw/audio/ac97: skip automatic zero-init of large arrays

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The 'read_audio' & 'write_audio' methods have a 4k byte array used
for copying data between the audio backend and device. Skip the
automatic zero-init of these arrays to eliminate the performance
overhead in the I/O hot path.

The 'tmpbuf' array will be fully initialized when reading data from
the audio backend and/or device memory.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20250610123709.835102-8-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2025-06-10 13:36:45 +01:00 • committed by Stefan Hajnoczi
parent 9a23075cef
commit 2553d2d26a
1 changed files with 2 additions and 2 deletions
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4
hw/audio/ac97.c
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@ -886,7 +886,7 @@ static void nabm_writel(void *opaque, uint32_t addr, uint32_t val)
static int write_audio(AC97LinkState *s, AC97BusMasterRegs *r, static int write_audio(AC97LinkState *s, AC97BusMasterRegs *r,
int max, int *stop) int max, int *stop)
{ {
uint8_t tmpbuf[4096]; QEMU_UNINITIALIZED uint8_t tmpbuf[4096];
uint32_t addr = r->bd.addr; uint32_t addr = r->bd.addr;
uint32_t temp = r->picb << 1; uint32_t temp = r->picb << 1;
uint32_t written = 0; uint32_t written = 0;
@ -959,7 +959,7 @@ static void write_bup(AC97LinkState *s, int elapsed)
static int read_audio(AC97LinkState *s, AC97BusMasterRegs *r, static int read_audio(AC97LinkState *s, AC97BusMasterRegs *r,
int max, int *stop) int max, int *stop)
{ {
uint8_t tmpbuf[4096]; QEMU_UNINITIALIZED uint8_t tmpbuf[4096];
uint32_t addr = r->bd.addr; uint32_t addr = r->bd.addr;
uint32_t temp = r->picb << 1; uint32_t temp = r->picb << 1;
uint32_t nread = 0; uint32_t nread = 0;