Re: [PATCH] BaseTools/tools_def: use separate PP definition for DTC

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 28 February 2018 at 02:41, Gao, Liming <liming.gao@intel.com> wrote:
> Reviewed-by: Liming Gao <liming.gao@intel.com>
>

Thanks all

Pushed as a68749f39a2e04ef68e5656b7b72fca25a2e23dc

>> -----Original Message-----
>> From: Leif Lindholm [mailto:leif.lindholm@linaro.org]
>> Sent: Wednesday, February 28, 2018 4:01 AM
>> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> Cc: edk2-devel@lists.01.org; Gao, Liming <liming.gao@intel.com>; Zhu, Yonghong <yonghong.zhu@intel.com>
>> Subject: Re: [PATCH] BaseTools/tools_def: use separate PP definition for DTC
>>
>> On Tue, Feb 27, 2018 at 07:02:06PM +0000, Ard Biesheuvel wrote:
>> > On 27 February 2018 at 18:58, Leif Lindholm <leif.lindholm@linaro.org> wrote:
>> > > On Tue, Feb 27, 2018 at 06:36:08PM +0000, Ard Biesheuvel wrote:
>> > >> On 27 February 2018 at 18:33, Leif Lindholm <leif.lindholm@linaro.org> wrote:
>> > >> > On Tue, Feb 27, 2018 at 05:51:32PM +0000, Ard Biesheuvel wrote:
>> > >> >> Clang's preprocessor behaves differently from GCC's, and produces
>> > >> >> intermediate device tree source that still contains #pragma pack()
>> > >> >> and other directives that the device tree compiler chokes on.
>> > >> >>
>> > >> >> For assembling device tree sources, it matters very little which
>> > >> >> preprocessor is being used, so let's just use GNU CPP explicitly.
>> > >> >
>> > >> > Ah, right, same fundamental issue as
>> > >> > 5b8766bb92debfa7b2f45a4a6d683b4227360d66.
>> > >>
>> > >> Yes, and I fail to see why changing just those two files makes a
>> > >> meaningful difference.
>> > >
>> > > Probably because Secure96Dxe.inf has a lot more [Packages] and
>> > > [LibraryClasses] dependencies than DeveloperBox.inf.
>> > >
>> > > This patch would undoubtedly also have resolved that issue.
>> > > (As would clang preprocessor not throwing out C syntax when explicitly
>> > > asked to provide asm.)
>> > >
>> > >> > However, this time triggered by autogen seemingly forcing inclusion of
>> > >> > lots of central header files that are not even used, like
>> > >> > MdePkg/Include/IndustryStandard/Bluetooth.h
>> > >> > MdePkg/Include/IndustryStandard/Acpi10.h
>> > >> > and so on.
>> > >> >
>> > >> > Is there any way to suppress these implicit includes from .dts
>> > >> > processing?
>> > >>
>> > >> There is 'Trim', which can filter #include'd content, but using that
>> > >> also robs us of the ability to #include .dtsi files, which was kind of
>> > >> the point of using the preprocessor in the first place.
>> > >
>> > > Yeah, that'd definitely be missing the point slightly.
>> > >
>> > > I was thinking more along the lines of either excluding the autogen
>> > > bits from the preprocessing or using a separate .inf for the .dts.
>> > >
>> >
>> > We need the AutoGen.h bits for the fixed PCD values, which was the
>> > other reason for using the preprocessor in the first place.
>>
>> Yeah, I was afraid of that.
>>
>> > Separate .inf would mean registering file GUIDs in the package .DEC,
>> > so that the driver can find the binary image at runtime, which is what
>> > I was trying to get away from by pulling it into the driver,
>> > especially because we are dealing with overlay DT snippets, of which
>> > there may be many, rather than a single DT (with a well known file
>> > GUID) for the entire platform.
>> >
>> > > If neither of those feels practical, the proposed patch is fine.
>> > > It just feels a little bit clunky.
>> >
>> > Yeah, I don't see any unclunky solutions, unfortunately.
>>
>> Fair enough.
>> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>