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hw/net/rtl8139: skip automatic zero-init of large array

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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 <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20250610123709.835102-20-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2025-06-10 13:36:57 +01:00 • committed by Stefan Hajnoczi
parent 6992c88683
commit 3ccc6489dd
1 changed files with 1 additions and 1 deletions
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2
hw/net/rtl8139.c
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@ -1816,7 +1816,7 @@ static int rtl8139_transmit_one(RTL8139State *s, int descriptor)
PCIDevice *d = PCI_DEVICE(s); PCIDevice *d = PCI_DEVICE(s);
int txsize = s->TxStatus[descriptor] & 0x1fff; 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", DPRINTF("+++ transmit reading %d bytes from host memory at 0x%08x\n",
txsize, s->TxAddr[descriptor]); txsize, s->TxAddr[descriptor]);