From 413a6fb4ee81897acafefb90f81ef3d2661c3aa6 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Tue, 6 Aug 2013 14:48:37 +0100 Subject: rombios/ata: Do not wait for BSY to be set After issuing a reset, the BSY bit is expected to be set. This is not the case for Qemu. In SeaBIOS.git: 580e33293244fee4556e56ecc67b8bd877f3c496 this check was even replaced with a udelay(5), as enough real hardware ignored the BSY bit as well. As rombios does not have an equivalent udelay(), replace the wait with a write to port 0x80 which is whitelisted by Xen for 'a small delay'. This causes 42k fewer IO traps to Qemu. Signed-off-by: Andrew Cooper Acked-by: Keir Fraser --- tools/firmware/rombios/rombios.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools/firmware') diff --git a/tools/firmware/rombios/rombios.c b/tools/firmware/rombios/rombios.c index e364759b3b..a3efc618e0 100644 --- a/tools/firmware/rombios/rombios.c +++ b/tools/firmware/rombios/rombios.c @@ -2914,8 +2914,8 @@ Bit16u device; // 8.2.1 (a) -- set SRST in DC outb(iobase2+ATA_CB_DC, ATA_CB_DC_HD15 | ATA_CB_DC_NIEN | ATA_CB_DC_SRST); -// 8.2.1 (b) -- wait for BSY - await_ide(BSY, iobase1, 20); +// 8.2.1 (b) -- wait + outb(0x80, 0x00); // 8.2.1 (f) -- clear SRST outb(iobase2+ATA_CB_DC, ATA_CB_DC_HD15 | ATA_CB_DC_NIEN); -- cgit v1.2.3