From: Daniel P. Berrangé Date: Tue, 10 Jun 2025 12:36:57 +0000 (+0100) Subject: hw/net/rtl8139: skip automatic zero-init of large array X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3ccc6489dd4925ddd1f3066bd3751389169cd7aa;p=thirdparty%2Fqemu.git hw/net/rtl8139: skip automatic zero-init of large array 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 --- 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]);