Re: 回复: [edk2-devel] [PATCH v2 00/13] BaseTools,CryptoPkg,MdePkg,OvmfPkg: Delete CLANG35,CLANG38,GCC48,GCC49, rename GCC5 to GCC, update CLANGDWARF, delete VS 2008-2013, EBC

["Ard Biesheuvel" <ardb@kernel.org>]

On Mon, 3 Apr 2023 at 14:15, Leif Lindholm <quic_llindhol@quicinc.com> wrote:
>
> On Mon, Apr 03, 2023 at 13:55:19 +0200, Ard Biesheuvel wrote:
> > I agree that we should either support a toolchain (and have CI
> > coverage for it) or not, in which case we should just remove it.
> >
> > However, the issues being reported are specific to SEV-SNP and TDX,
> > which implies that they are specific to OVMF. And actually, the
> > reported issue at
> >
> > OvmfPkg/Library/CcExitLib/CcExitVcHandler.c:1358:10:
> > error: ‘XCr0’ may be used uninitialized [-Werror=maybe-uninitialized]
> >
> > seems to be a valid concern.
> >
> > So the point I am making is that OVMF gets a lot of attention in the
> > open source project, but in the wider ecosystem, there are many
> > platforms relying on this code base that don't incorporate the Coco
> > components at all, so whether OVMF currently builds with GCC49 is not
> > 100% relevant.
> >
> > So I am leaning towards retaining GCC49 as GCCNOLTO, and getting some
> > coverage for it in CI, as we occasionally get useful diagnostics out
> > of it. But I am not going to fight any battles over it - I rarely use
> > it myself, and so I will not miss it when it's gone.
>
> I agree with all aspects of this statement. I would *prefer* to keep
> it as a canary - with CI.
>

Cheers.

And interestingly, GCC49 appears to spot an issue introduced with commit

commit a7fcab7aa3de338c02e61fd891610b1ec926e6c8
Author: Hua Ma <hua.ma@intel.com>
Date:   Mon Oct 11 11:43:12 2021 +0800

    MdeModulePkg/Core/Dxe: Acquire a lock when iterating gHandleList

where we may end up dereferencing a bogus 'Prot' pointer:

MdeModulePkg/Core/Dxe/Hand/Handle.c:1198:24:
error: ‘Prot’ may be used uninitialized [-Werror=maybe-uninitialized]
 1198 |       *Interface = Prot->Interface;
      |                    ~~~~^~~~~~~~~~~
MdeModulePkg/Core/Dxe/Hand/Handle.c:994:24:
note: ‘Prot’ was declared here
  994 |   PROTOCOL_INTERFACE  *Prot;

So I am going to change my mind, and state that I do care about GCC
non-LTO builds, as we have been introducing bugs into our code that we
could have spotted if anyone had bothered to test with this toolchain
config.