Re: [edk2-devel] [edk2-discuss] [Bug]: EmbeddedPkg/VirtualRealTimeClockLib fails to build.

["Leif Lindholm via groups.io" <leif.lindholm=oss.qualcomm.com@groups.io>]

On Thu, 26 Jun 2025 at 22:25, Kinney, Michael D
<michael.d.kinney@intel.com> wrote:
> EmbeddedPkg/VirtualRealTimeClockLib change:
> https://github.com/mdkinney/edk2/commit/51430285377e4d6298ec2b3ea9243d1c8ef9fb2a

Yes, this approach is defnitely what we want for the module.

> BaseTools change:
> https://github.com/mdkinney/edk2/commit/a596ddc61d649e52db861e0fb6613c0a47336b6e

A few thoughs about this one:
- Clearly the naming builds on SOURCE_DATE_EPOCH. Is there value in
adding our own prefix?
  - If we do add our own prefix, is there a corresponding change in semantics?
  - Alternatively, could we do an "if not defined SOURCE_DATE_EPOCH,
..., set SOURCE_DATE_EPOCH
    to current time"?

/
    Leif

> Mike
>
> > -----Original Message-----
> > From: Leif Lindholm <leif.lindholm@oss.qualcomm.com>
> > Sent: Thursday, June 26, 2025 1:03 PM
> > To: Kinney, Michael D <michael.d.kinney@intel.com>
> > Cc: discuss@edk2.groups.io; rithrama@amd.com; Michael Kubacki
> > <mikuback@linux.microsoft.com>; edk2-devel-groups-io <devel@edk2.groups.io>
> > Subject: Re: [edk2-discuss] [Bug]: EmbeddedPkg/VirtualRealTimeClockLib
> > fails to build.
> >
> > Hi Mike,
> >
> > I like that idea. Sounds like something that could be useful in other
> > places as well.
> >
> > Regards,
> >
> > Leif
> >
> > On Thu, 26 Jun 2025 at 20:02, Kinney, Michael D
> > <michael.d.kinney@intel.com> wrote:
> > >
> > > Hi Leif,
> > >
> > > I have looked at this and suggest we add a new env var to the edk2 build
> > > that captures the EPOCH value in python code and sets the env var and
> > > that env var can be used in INF files removing the use of OS specific
> > > commands.
> > >
> > > Will require change to EDK II Build Spec and BaseTools.
> > >
> > > Also need to support override of EPOCH value to a constant value to
> > > support reproducible builds.
> > >
> > > I have a POC of this that I can share.
> > >
> > > Mike
> > >
> > >
> > > > -----Original Message-----
> > > > From: discuss@edk2.groups.io <discuss@edk2.groups.io> On Behalf Of Leif
> > > > Lindholm via groups.io
> > > > Sent: Thursday, June 26, 2025 2:59 AM
> > > > To: rithrama@amd.com
> > > > Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Michael Kubacki
> > > > <mikuback@linux.microsoft.com>; discuss@edk2.groups.io; edk2-devel-
> > groups-
> > > > io <devel@edk2.groups.io>
> > > > Subject: Re: [edk2-discuss] [Bug]: EmbeddedPkg/VirtualRealTimeClockLib
> > > > fails to build.
> > > >
> > > > On Wed, 25 Jun 2025 at 23:14, Rithvik Rama via groups.io
> > > > <rithrama=amd.com@groups.io> wrote:
> > > > > The EmulatorPkg throws below error when running a build:
> > > > >
> > > >
> > edk2\EmbeddedPkg\Library\VirtualRealTimeClockLib\VirtualRealTimeClockLib.c(
> > > > 89): error C2065: 'BUILD_EPOCH': undeclared identifier
> > > >
> > > > I don't see EmbeddedPkg referenced in EmulatorPkg. Is EmulatorPkg a
> > typo
> > > > above?
> > > >
> > > > > The reason I raised this discussion is because the source file
> > comments
> > > > asks me to bring this up with the mailing list:
> > > > > //
> > > > >     // The following is intended to produce a compilation error on
> > build
> > > > >     // environments where BUILD_EPOCH can not be set from inline
> > shell.
> > > > >     // If you are attempting to use this library on such an
> > environment,
> > > > please
> > > > >     // contact the edk2 mailing list, so we can try to add support
> > for
> > > > it.
> > > > >     //
> > > > >
> > > > > The toolchain I used:
> > > > > VS2022
> > > > > Windows 11.
> > > > >
> > > > > May I know the root cause of this issue and how do I continue to
> > build
> > > > the EmbeddedPkg successfully?
> > > >
> > > > The answer is simple. A lot of EmbeddedPkg has only been tested
> > > > with/developed for GCC family of
> > > > toolchains.
> > > >
> > > > For those, we generate the BUILD_EPOCH here:
> > > >
> > https://github.com/tianocore/edk2/blob/master/EmbeddedPkg/Library/VirtualRe
> > > > alTimeClockLib/VirtualRealTimeClockLib.inf#L37
> > > >   GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`printenv SOURCE_DATE_EPOCH ||
> > date
> > > > +%s`
> > > > only sets BUILD_EPOCH for GCC family of toolchains.
> > > >
> > > > I don't know how to best wrangle this together for a Visual Studio
> > > > environment.
> > > > Maybe a better way there would be to do something with __DATE__ and
> > > > __TIME__ macros,
> > > > but I don't think the formats of those are portable between toolchains.
> > > > Mike, Michael - thoughts?
> > > >
> > > > A hack that would let you build this would be to add a line like such:
> > > >   MSFT:*_*_*_CC_FLAGS = -DBUILD_EPOCH=1750931236
> > > > (timestamp generated by me in a linux shell with "git log -1
> > > > --pretty=%ct | date +%s")
> > > >
> > > > /
> > > >     Leif
> > > >
> > > >
> > > > 
> > > >
> > >


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