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authorDaniel P. Berrangé <berrange@redhat.com>2025-06-10 13:36:58 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2025-06-12 13:40:15 -0400
commite1afd5ee6eb2954f4baf3c97820e4aaf7de97d2a (patch)
tree43c76f284f4c53e2746963063844422ff233e8e1
parent3ccc6489dd4925ddd1f3066bd3751389169cd7aa (diff)
downloadfocaccia-qemu-e1afd5ee6eb2954f4baf3c97820e4aaf7de97d2a.tar.gz
focaccia-qemu-e1afd5ee6eb2954f4baf3c97820e4aaf7de97d2a.zip
hw/net/tulip: skip automatic zero-init of large array
The 'tulip_setup_frame' method has a 4k byte array used for copynig
DMA data from the device. Skip the automatic zero-init of this array
to eliminate the performance overhead in the I/O hot path.

The 'buf' array will be fully initialized when reading data from the
device.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20250610123709.835102-21-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r--hw/net/tulip.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/hw/net/tulip.c b/hw/net/tulip.c
index 63fe513458..319af906c8 100644
--- a/hw/net/tulip.c
+++ b/hw/net/tulip.c
@@ -629,7 +629,7 @@ static void tulip_setup_filter_addr(TULIPState *s, uint8_t *buf, int n)
 static void tulip_setup_frame(TULIPState *s,
         struct tulip_descriptor *desc)
 {
-    uint8_t buf[4096];
+    QEMU_UNINITIALIZED uint8_t buf[4096];
     int len = (desc->control >> TDES1_BUF1_SIZE_SHIFT) & TDES1_BUF1_SIZE_MASK;
     int i;