Re: [PATCH 2/2] ArmVirtPkg ARM: make relocatable PrePi users build with CLANG35

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

On 3 August 2016 at 13:19, Laszlo Ersek <lersek@redhat.com> wrote:
> On 08/03/16 12:02, Ard Biesheuvel wrote:
>> On 3 August 2016 at 12:00, Laszlo Ersek <lersek@redhat.com> wrote:
>>> On 08/03/16 10:21, Ard Biesheuvel wrote:
>>>> The clang developers have made a backward incompatible change to the
>>>> command line arguments, and have replaced '-mllvm -arm-use-movt=0'
>>>> with '-mno-movt'. This does not matter for most ARM platforms, and
>>>> therefore it has been removed from the default CLANG35/ARM CC flags
>>>> in patch 1c63516075b3 ("BaseTools CLANG35: drop problematic use-movt
>>>> and save-temps options"), but as it turns out, the relocatable PrePi
>>>> implementation used by ArmVirtQemuKernel and ArmVirtXen will fail to
>>>> build if it contains MOVT/MOVW pairs, due to the fact that these are
>>>> not runtime relocatable under ELF.
>>>>
>>>> Since they are runtime relocatable under PE/COFF, and GenFw does the
>>>> right thing when encountering them, selectively controlling their
>>>> use is more appropriate than disabling them altogether. Therefore,
>>>> this patch adds the -mno-movt argument only for the platforms that
>>>> use the relocatable PrePi, and only for the module types that may
>>>> be pulled into its build.
>>>>
>>>> Contributed-under: TianoCore Contribution Agreement 1.0
>>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>> ---
>>>>  ArmVirtPkg/ArmVirtQemuKernel.dsc | 8 ++++++++
>>>>  ArmVirtPkg/ArmVirtXen.dsc        | 9 +++++++++
>>>>  2 files changed, 17 insertions(+)
>>>>
>>>> diff --git a/ArmVirtPkg/ArmVirtQemuKernel.dsc b/ArmVirtPkg/ArmVirtQemuKernel.dsc
>>>> index 01a1d9b4613b..6c536d9bbd2d 100644
>>>> --- a/ArmVirtPkg/ArmVirtQemuKernel.dsc
>>>> +++ b/ArmVirtPkg/ArmVirtQemuKernel.dsc
>>>> @@ -45,6 +45,9 @@ [LibraryClasses.ARM]
>>>>    ArmLib|ArmPkg/Library/ArmLib/ArmV7/ArmV7Lib.inf
>>>>    ArmCpuLib|ArmPkg/Drivers/ArmCpuLib/ArmCortexA15Lib/ArmCortexA15Lib.inf
>>>>
>>>> +[LibraryClasses.ARM.SEC]
>>>> +  ArmLib|ArmPkg/Library/ArmLib/ArmV7/ArmV7LibSec.inf
>>>> +
>>>
>>> How does this library resolution change relate to the stated purpose of
>>> the patch?
>>>
>>
>> It prevents a version of ArmLib being pulled into the build of the
>> relocatable PrePi that was built using the BuildOptions for DXE_DRIVER
>> type modules.
>>
>
> I think it would be reasonable to add this one paragraph to the commit
> message as well. If you disagree, I won't insist. :)
>

No, you're quite right. I'm still a bit confused that a SEC module can
include DXE_DRIVER type libraries, but I guess it doesn't matter if
there is no constructor.

> Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thank you,
Ard.