From: Daniel P. Berrangé <berrange@redhat.com>
Date: Tue, 10 Jun 2025 12:37:05 +0000 (+0100)
Subject: hw/scsi/lsi53c895a: skip automatic zero-init of large array
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=55243edf42ee87bce9f36ca251f3ab9cda1563e4;p=thirdparty%2Fqemu.git

hw/scsi/lsi53c895a: skip automatic zero-init of large array

The 'lsi_memcpy' method has a 4k byte array used for copying data
to/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 data is copied.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Message-id: 20250610123709.835102-28-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---

diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
index f4f2ef321e..9ea4aa0a85 100644
--- a/hw/scsi/lsi53c895a.c
+++ b/hw/scsi/lsi53c895a.c
@@ -1112,7 +1112,7 @@ bad:
 static void lsi_memcpy(LSIState *s, uint32_t dest, uint32_t src, int count)
 {
     int n;
-    uint8_t buf[LSI_BUF_SIZE];
+    QEMU_UNINITIALIZED uint8_t buf[LSI_BUF_SIZE];
 
     trace_lsi_memcpy(dest, src, count);
     while (count) {