Reviewed-by: Jordan Justen <jordan.l.jus...@intel.com>
On 2017-09-27 18:03:53, Jian J Wang wrote:
> QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
> detection is enabled, this driver will fail to load. NULL pointer detection
> bypassing code is added to prevent such problem during boot.
>
> Please note that Windows 7 will try to access VBE SHIM during boot if it's
> installed, and then cause boot failure. This can be fixed by setting BIT7
> of PcdNullPointerDetectionPropertyMask to disable NULL pointer detection
> after EndOfDxe. As far as we know, there's no other OSs has such issue.
>
> > According to Laszlo, remove the code disabling/enabling the NULL pointer
> > detection but just ignore the installing if it's enabled
>
> Cc: Star Zeng <star.z...@intel.com>
> Cc: Eric Dong <eric.d...@intel.com>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Jiewen Yao <jiewen....@intel.com>
> Cc: Michael Kinney <michael.d.kin...@intel.com>
> Cc: Jordan Justen <jordan.l.jus...@intel.com>
> Cc: Ayellet Wolman <ayellet.wol...@intel.com>
> Suggested-by: Ayellet Wolman <ayellet.wol...@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.w...@intel.com>
> ---
> OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf | 1 +
> OvmfPkg/QemuVideoDxe/VbeShim.c | 14 ++++++++++++++
> 2 files changed, 15 insertions(+)
>
> diff --git a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> index 577e07b0a8..ff68c99e96 100644
> --- a/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> +++ b/OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
> @@ -77,3 +77,4 @@
> [Pcd]
> gOptionRomPkgTokenSpaceGuid.PcdDriverSupportedEfiVersion
> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
> + gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
> diff --git a/OvmfPkg/QemuVideoDxe/VbeShim.c b/OvmfPkg/QemuVideoDxe/VbeShim.c
> index e45a08e887..8ba5522cde 100644
> --- a/OvmfPkg/QemuVideoDxe/VbeShim.c
> +++ b/OvmfPkg/QemuVideoDxe/VbeShim.c
> @@ -75,6 +75,20 @@ InstallVbeShim (
> UINTN Printed;
> VBE_MODE_INFO *VbeModeInfo;
>
> + if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & (BIT0|BIT7)) == BIT0)
> {
> + DEBUG ((
> + DEBUG_WARN,
> + "%a: page 0 protected, not installing VBE shim\n",
> + __FUNCTION__
> + ));
> + DEBUG ((
> + DEBUG_WARN,
> + "%a: page 0 protection prevents Windows 7 from booting anyway\n",
> + __FUNCTION__
> + ));
> + return;
> + }
> +
> Segment0 = 0x00000;
> SegmentC = 0xC0000;
> SegmentF = 0xF0000;
> --
> 2.14.1.windows.1
>
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