Reviewed-by: Jordan Justen <[email protected]>
On 2015-07-24 16:00:07, Laszlo Ersek wrote: > We have an old bug in BootModeInitialization(): firmware is supposed to > clear the CMOS register 0xF after reading it for the last time. QEMU only > sets this register to 0xFE in "hw/timer/mc146818rtc.c", function > rtc_notify_suspend(), and never clears it. However, SeaBIOS does clear it > in "src/post.c" and "src/resume.c", so let's follow suit. > > We've never noticed this until now because the register gets mysteriously > cleared on non-resume reboots when OVMF runs on qemu-system-x86_64. But on > qemu-system-i386, this bug breaks a (suspend, resume, reboot) triplet: > after the last step OVMF thinks it's resuming because when it actually > resumed (in the middle step), it failed to clear the register. > > BootModeInitialization() is the perfect function to clear the register, > right after setting mBootMode: the function is executed on both normal > boot and on S3 resume; it succeeds DebugDumpCmos() -- so the dump is not > affected by this patch --; and everything that relies on S3 vs. normal > boot after we clear the register uses mBootMode anyway. > > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Laszlo Ersek <[email protected]> > --- > OvmfPkg/PlatformPei/Platform.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c > index fc98fc3..d7b1d41 100644 > --- a/OvmfPkg/PlatformPei/Platform.c > +++ b/OvmfPkg/PlatformPei/Platform.c > @@ -324,6 +324,7 @@ BootModeInitialization ( > if (CmosRead8 (0xF) == 0xFE) { > mBootMode = BOOT_ON_S3_RESUME; > } > + CmosWrite8 (0xF, 0x00); > > Status = PeiServicesSetBootMode (mBootMode); > ASSERT_EFI_ERROR (Status); > -- > 1.8.3.1 > > > _______________________________________________ > edk2-devel mailing list > [email protected] > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
