Re: [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL pointer detection during VBE SHIM installing

[Laszlo Ersek <lersek@redhat.com>]

On 10/10/17 03:50, Wang, Jian J wrote:
> I have summary in each patch email.

Sure, you have a commit message, but you didn't point out any v3->v4
changes. (If there are no v3->v4 changes, then please pick up the R-b's
received for v3.)

> I removed the CC of some patches because 
> there's no update from v3 to v4. I thought this could remind you of this situation.
> What's the recommended way? Keep the CC as-was and just add summaries in 
> cover letter?

Maintainers should always be CC'd, even if there are no changes relative
to the previous version.

Personally I prefer summarizing the changes in the cover letter, and
also explaining the changes in more detail -- or pointing out the lack
of any changes -- on each individual patch.

If you have a bit of time for reading, I recommend the following wiki
article:

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers

In it, I had written down most everything that I have in mind about the
edk2 development process. The following steps pertain to the current
discussion (i.e., picking up feedback tags, adding Maintainer CC's, and
pointing out changes per patch):

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers#contrib-18

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers#contrib-28

https://github.com/tianocore/tianocore.github.io/wiki/Laszlo's-unkempt-git-guide-for-edk2-contributors-and-maintainers#contrib-30

Thanks,
Laszlo


> 
>> -----Original Message-----
>> From: Laszlo Ersek [mailto:lersek@redhat.com]
>> Sent: Monday, October 09, 2017 11:56 PM
>> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
>> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Wolman, Ayellet
>> <ayellet.wolman@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Dong, Eric
>> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>
>> Subject: Re: [edk2] [PATCH v4 6/6] OvmfPkg/QemuVideoDxe: Bypass NULL
>> pointer detection during VBE SHIM installing
>>
>> On 10/09/17 17:54, Laszlo Ersek wrote:
>>> On 10/09/17 16:17, 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.
>>>>
>>>> Cc: Star Zeng <star.zeng@intel.com>
>>>> Cc: Eric Dong <eric.dong@intel.com>
>>>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>>>> Cc: Michael Kinney <michael.d.kinney@intel.com>
>>>> Cc: Ayellet Wolman <ayellet.wolman@intel.com>
>>>> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
>>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>>> Signed-off-by: Jian J Wang <jian.j.wang@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;
>>>>
>>>
>>> If this patch is entirely identical to the previous version (v3), then
>>> you should have please picked up the review tags from Jordan and myself,
>>> the ones that you got for v3:
>>>
>>> http://mid.mail-
>> archive.com/150696711831.2454.16712170525103415248@jljusten-skl
>>>
>>> http://mid.mail-archive.com/d1a20be5-8dbf-8ce6-1738-
>> d03b330047cc@redhat.com
>>>
>>> This way we can quickly filter out already reviewed patches, and avoid
>>> re-reviewing when there are no changes.
>>>
>>>
>>> Your cover letter v4 0/6 also does not summarize the changes relative to
>>> v3; in the future please don't forget about that.
>>
>> ... personal CC's for OvmfPkg maintainers and reviewers are also missing
>> from this patch. Please check "Maintainers.txt" every time.
>>
>> Thanks
>> Laszlo