From: Daniel P. Berrangé Date: Tue, 10 Jun 2025 12:36:46 +0000 (+0100) Subject: hw/audio/cs4231a: skip automatic zero-init of large arrays X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ca2cc0385d97cea66cd54ee42553f385c403d4a6;p=thirdparty%2Fqemu.git hw/audio/cs4231a: skip automatic zero-init of large arrays The 'cs_write_audio' method has a pair of byte arrays, one 4k in size and one 8k, which are used in converting audio samples. 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 a block of data from the guest. The 'linbuf' array will be fully initialized when converting the audio samples. Signed-off-by: Daniel P. Berrangé Reviewed-by: Stefan Hajnoczi Message-id: 20250610123709.835102-9-berrange@redhat.com Signed-off-by: Stefan Hajnoczi --- diff --git a/hw/audio/cs4231a.c b/hw/audio/cs4231a.c index eb9a45805b..6dfff202ff 100644 --- a/hw/audio/cs4231a.c +++ b/hw/audio/cs4231a.c @@ -528,7 +528,7 @@ static int cs_write_audio (CSState *s, int nchan, int dma_pos, int dma_len, int len) { int temp, net; - uint8_t tmpbuf[4096]; + QEMU_UNINITIALIZED uint8_t tmpbuf[4096]; IsaDmaClass *k = ISADMA_GET_CLASS(s->isa_dma); temp = len; @@ -547,7 +547,7 @@ static int cs_write_audio (CSState *s, int nchan, int dma_pos, copied = k->read_memory(s->isa_dma, nchan, tmpbuf, dma_pos, to_copy); if (s->tab) { int i; - int16_t linbuf[4096]; + QEMU_UNINITIALIZED int16_t linbuf[4096]; for (i = 0; i < copied; ++i) linbuf[i] = s->tab[tmpbuf[i]];