On Thu, Oct 26, 2017 at 9:48 AM, Laszlo Ersek <[email protected]> wrote: > Clearing I/O port decoding in the PCI command register at > ExitBootServices() breaks IDE boot in Windows, on QEMU's "pc" (i440fx) > machine type. (AHCI boot on "q35" is unaffected.) Windows seems repeatedly > stuck, apparently waiting for a timeout of sorts. > > This is arguably a Windows bug; a native OS driver should not expect the > firmware to leave the PCI command register in any particular state. > > Strictly speaking, we only need to disable BM-DMA at ExitBootServices(), > in order to abort pending transfers to/from RAM, which is soon to be owned > by the OS. BM-DMA is also the only bit that's explicitly named by the UEFI > Driver Writers' Guide, for clearing at ExitBootServices(). > > I've verified that clearing only BM-DMA fixes the isse (boot time) on > i440fx, and does not regress q35/AHCI.
Worked for my test case (booting a Win10 install ISO in ~30s). Thanks Laszlo! Tested-by: dann frazier <[email protected]> _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
