[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2 of 5] rombios/ata: Do not wait for BSY to be set
I can't find any guarantee in the ATA specification that this will happen, and it certainly does not with Qemu. SeaBIOS has replaced it with a call to udelay(5) instead. 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 roughly 42k fewer traps to Qemu, which is very roughly 10% of the number of traps during boot of a Win7 guest. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> diff -r 1728fb789940 -r c223c044afbf tools/firmware/rombios/rombios.c --- 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); _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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