From 14997d521d1cd0bb36c902ef1032f0d3f2a3c912 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Tue, 10 Jun 2025 13:37:04 +0100 Subject: [PATCH] hw/usb/hcd-ohci: skip automatic zero-init of large array MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The 'ohci_service_iso_td' 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 'buf' array will be fully initialized when reading data from guest memory. Signed-off-by: Daniel P. Berrangé Reviewed-by: Stefan Hajnoczi Reviewed-by: Klaus Jensen Reviewed-by: Harsh Prateek Bora Message-id: 20250610123709.835102-27-berrange@redhat.com Signed-off-by: Stefan Hajnoczi --- hw/usb/hcd-ohci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c index 71b54914d3..72a9f9f474 100644 --- a/hw/usb/hcd-ohci.c +++ b/hw/usb/hcd-ohci.c @@ -577,7 +577,7 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed) USBDevice *dev; USBEndpoint *ep; USBPacket *pkt; - uint8_t buf[8192]; + QEMU_UNINITIALIZED uint8_t buf[8192]; bool int_req; struct ohci_iso_td iso_td; uint32_t addr; -- 2.39.5