From 3ccc6489dd4925ddd1f3066bd3751389169cd7aa Mon Sep 17 00:00:00 2001 From: =?utf8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Tue, 10 Jun 2025 13:36:57 +0100 Subject: [PATCH] hw/net/rtl8139: skip automatic zero-init of large array MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The 'rtl8139_transmit_one' method has a 8k byte array used for copying data between guest and host. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'txbuffer' will be fully initialized when reading PCI DMA buffers. Signed-off-by: Daniel P. Berrangé Reviewed-by: Stefan Hajnoczi Message-id: 20250610123709.835102-20-berrange@redhat.com Signed-off-by: Stefan Hajnoczi --- hw/net/rtl8139.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c index 15b8f7501a..654a087d80 100644 --- a/hw/net/rtl8139.c +++ b/hw/net/rtl8139.c @@ -1816,7 +1816,7 @@ static int rtl8139_transmit_one(RTL8139State *s, int descriptor) PCIDevice *d = PCI_DEVICE(s); int txsize = s->TxStatus[descriptor] & 0x1fff; - uint8_t txbuffer[0x2000]; + QEMU_UNINITIALIZED uint8_t txbuffer[0x2000]; DPRINTF("+++ transmit reading %d bytes from host memory at 0x%08x\n", txsize, s->TxAddr[descriptor]); -- 2.39.5