Re: [PATCH v4 0/7] BaseTools: add support for GCC5 in LTO mode

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

On 29 July 2016 at 06:47, Gao, Liming <liming.gao@intel.com> wrote:
> Ard:
>   Thanks for your update. I have some comments for them.
> 1) It uses GCC as Link for GCC44-GCC49. Have you done verification on them? I verify GCC49 in OVMFIa32X64 platform. It works.

Yes, I tested all of them.

> 2) After this change, how to append new link option in platform DSC? Use style -Wl, ?

It depends. Some options (like -z) don't need it, but others do.

> 3) I see GCC5 uses gcc-ar as its SLINK, and GCC49 uses ar as its SLINK. Is gcc-ar required only by LTO?

Yes

> 4) Before GCC49 optimization, GCC49 means GCC49 or later, GCC5 can work with GCC49 tool chain configuration. But now, I configure gcc to point to GCC5, and build OVMF with GCC49 tool chain, it reports GenFw failure. I expect GCC5 work with GCC49 and GCC5 tool chain both. GCC49 for no lto, GCC5 for lto. I know Steven has provided the patch to fix this GenFw issue.
>
> GenFw: ERROR 3000: Invalid
>   /home/hwu/work/lgao4/AllPkg/Build/Ovmf3264/DEBUG_GCC49/X64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll unsupported ELF EM_X86_64 relocation 0x9.
> GenFw: ERROR 3000: Invalid
>   /home/hwu/work/lgao4/AllPkg/Build/Ovmf3264/DEBUG_GCC49/X64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll unsupported ELF EM_X86_64 relocation 0x9.
> GenFw: ERROR 3000: Invalid
>

Which GCC version are you using?


>> -----Original Message-----
>> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>> Sent: Wednesday, July 27, 2016 7:14 PM
>> To: edk2-devel@lists.01.org; lersek@redhat.com; Gao, Liming
>> <liming.gao@intel.com>; Shi, Steven <steven.shi@intel.com>; Zhu,
>> Yonghong <yonghong.zhu@intel.com>; Justen, Jordan L
>> <jordan.l.justen@intel.com>
>> Cc: leif.lindholm@linaro.org; Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> Subject: [PATCH v4 0/7] BaseTools: add support for GCC5 in LTO mode
>>
>> This v4 to introduce GCC5 is now a 7 piece series, including some
>> preparatory cleanup patches that allow all GCC4x and CLANG35 toolchains
>> to switch to using 'gcc' as the linker. This allows us to get rid of
>> the wrapper script to marshall ld arguments in order to make them
>> understandable by gcc, which is fragile and likely to cause problems in
>> the future.
>>
>> Since there appears to be a natural split between the 'legacy' GCC
>> toolchains UNIXGCC, ELFGCC, and CYGGCC[xASL], both in term of supported
>> architectures [IA32, X64, IPF] vs [IA32, X64, ARM, AARCH64], and in
>> terms of maintenance, these toolchains are not moved to using 'gcc' as
>> the linker, and instead, a new BUILDRULEFAMILY is introduced called GCCLD
>> that will retain the old behavior.
>>
>> The result is that GCC5 can align much more closely with its predecessors,
>> making the expected maintenance burden of supporting GCC back to v4.4
>> much lower.
>>
>> Changes since v3:
>> - like Steven does in his GCC5LTO patch, add -fno-builtin to IA32 and X64
>>   CC_FLAGS; this addresses a build issue reported by Liming
>> - add -Os the the linker flags as well, for AARCH64 this does not seem to
>> make
>>   a difference, but it is arguably correct since the LTO processing at link
>>   time involves code generation as well
>> - add Laszlo's ack to #2
>> - new patch #6 to omit the autogenerated build-id from the PE/COFF binary
>>
>> Changes since v2:
>> - add license headers to LTO glue files for ARM and AARCH64 (#5)
>> - get rid of lto-ld-wrapper script
>>
>> Ard Biesheuvel (7):
>>   BaseTools CLANG35: drop problematic use-movt and save-temps options
>>   ArmVirtPkg/ArmVirtPrePiUniCoreRelocatable: ignore .hash and .note
>>     sections
>>   BaseTools UNIXGCC ELFGCC CYGGCC: clone GCC build rule family into
>>     GCCLD
>>   BaseTools GCC: use 'gcc' as the linker command for GCC44 and later
>>   ArmPkg: add prebuilt glue binaries for GCC5 LTO support
>>   BaseTools GCC: drop GNU notes section from EFI image
>>   BaseTools GCC: add support for GCC v5.x in LTO mode
>>
>>  ArmPkg/GccLto/liblto-aarch64.a                      | Bin 0 -> 1016 bytes
>>  ArmPkg/GccLto/liblto-aarch64.s                      |  27 ++
>>  ArmPkg/GccLto/liblto-arm.a                          | Bin 0 -> 2096 bytes
>>  ArmPkg/GccLto/liblto-arm.s                          |  61 ++++
>>  ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf |   2 +-
>>  ArmVirtPkg/PrePi/Scripts/PrePi-PIE.lds              |   3 +
>>  BaseTools/Conf/build_rule.template                  |  31 +-
>>  BaseTools/Conf/tools_def.template                   | 344 ++++++++++++++------
>>  BaseTools/Scripts/GccBase.lds                       |   6 +
>>  EmulatorPkg/Unix/Host/Host.inf                      |   6 +-
>>  10 files changed, 372 insertions(+), 108 deletions(-)
>>  create mode 100644 ArmPkg/GccLto/liblto-aarch64.a
>>  create mode 100644 ArmPkg/GccLto/liblto-aarch64.s
>>  create mode 100644 ArmPkg/GccLto/liblto-arm.a
>>  create mode 100644 ArmPkg/GccLto/liblto-arm.s
>>
>> --
>> 2.7.4
>