Re: [edk2-devel] OvmfPkgX64 doesn't build with CLANG38 (clang 14.0.3) NOOPT - undefined reference to `memcpy'

["Pedro Falcato" <pedro.falcato@gmail.com>]

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Is there a legitimate reason not to define memcpy? It'd be easier to do so
and comply to the compiler's requirements.

On Wed, 25 May 2022, 23:38 Yao, Jiewen, <jiewen.yao@intel.com> wrote:

> Hi
>
> Would you please use CopyMem() for the structure assignment?
>
> VgpuGop->GopModeInfo  = *GopModeInfo;
>
>
>
> That is best known method to resolve memcpy symbol issue.
>
>
>
> Thank you
>
> Yao Jiewen
>
>
>
>
>
> *From:* Pedro Falcato <pedro.falcato@gmail.com>
> *Sent:* Thursday, May 26, 2022 1:01 AM
> *To:* Ard Biesheuvel <ardb@kernel.org>
> *Cc:* edk2-devel-groups-io <devel@edk2.groups.io>; Rebecca Cran <
> quic_rcran@quicinc.com>; Ard Biesheuvel <ardb+tianocore@kernel.org>; Yao,
> Jiewen <jiewen.yao@intel.com>; Justen, Jordan L <jordan.l.justen@intel.com>;
> Gerd Hoffmann <kraxel@redhat.com>
> *Subject:* Re: [edk2-devel] OvmfPkgX64 doesn't build with CLANG38 (clang
> 14.0.3) NOOPT - undefined reference to `memcpy'
>
>
>
> On Wed, May 25, 2022 at 5:45 PM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Wed, 25 May 2022 at 18:44, Pedro Falcato <pedro.falcato@gmail.com>
> wrote:
> >
> >
> >
> > On Wed, May 25, 2022 at 4:50 PM Ard Biesheuvel <ardb@kernel.org> wrote:
> >>
> >> On Wed, 25 May 2022 at 17:08, Rebecca Cran <quic_rcran@quicinc.com>
> wrote:
> >> >
> >> > I noticed OvmfPkg/OvmfPkgX64.dsc doesn't build with `-t CLANG38 -b
> >> > NOOPT` (with clang version 14.0.2) with the latest edk2 master
> >> > (07c0c2eb0a5970db614ebce1060fc79d6904bdfd):
> >> >
> >> > make: Nothing to be done for 'tbuild'.
> >> > /usr/bin/ld: /usr/bin/ld: DWARF error: invalid or unhandled FORM
> value:
> >> > 0x23
> >> >
> /home/bcran/src/upstream/uefi/edk2/Build/OvmfX64/NOOPT_CLANG38/X64/OvmfPkg/VirtioGpuDxe/VirtioGpu/OUTPUT/VirtioGpuDxe.lib(Gop.obj):
> >> > in function `GopSetMode':
> >> > Gop.c:(.text.GopSetMode+0x418): undefined reference to `memcpy'
> >>
> >> Can you dump the object file to see where the memcpy() call is emitted?
> >
> > I think I found the smoking gun:
> https://github.com/tianocore/edk2/blob/916f90baa547b3ebef8fa87c530e2f0c8e35e1e3/OvmfPkg/VirtioGpuDxe/Gop.c#L512
>
> Indeed. We don't support struct assignment in Tianocore code, exactly
> for this reason.
>
> Note: We should think about providing some basic libc functions in base
> EDK2 as some are required by the clang/GCC compilers (see
> https://gcc.gnu.org/onlinedocs/gcc/Standards.html, grep for memcpy or
> freestanding).
>
> Passing -ffreestanding would also be a good idea as to let the compiler
> know it's dealing with a freestanding environment vs a hosted user-space
> one.
>
>
>
> All the best,
>
> Pedro
>

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