Re: [edk2-devel] [PATCH] OvmfPkg/X86QemuLoadImageLib: add dummy assignment to work around GCC

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

On Wed, 25 Mar 2020 at 20:08, Laszlo Ersek <lersek@redhat.com> wrote:
>
> On 03/25/20 10:12, Ard Biesheuvel wrote:
> > GCC 4.8 or 4.9 may throw the following error when building OVMF:
> >
> >   Edk2/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c:
> >       In function ‘QemuLoadKernelImage’:
> >   Edk2/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c:416:30:
> >       error: ‘CommandLine’ may be used uninitialized in this function
> >                                                [-Werror=maybe-uninitialized]
> >         UnicodeSPrintAsciiFormat (
> >         cc1: all warnings being treated as errors
> >
> > This is due to the fact that older GCCs fail to infer that CommandLine is
> > never actually used unless it has been assigned. So add a redundant NULL
> > assignment to help these older GCCs understand this.
> >
> > Link: https://bugzilla.tianocore.org/show_bug.cgi?id=2630
> > Fixes: 7c47d89003a6f ("OvmfPkg: implement QEMU loader library for X86 with ...")
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
> >  OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c b/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c
> > index c5bd6862b265..52b14a4462d8 100644
> > --- a/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c
> > +++ b/OvmfPkg/Library/X86QemuLoadImageLib/X86QemuLoadImageLib.c
> > @@ -291,6 +291,11 @@ QemuLoadKernelImage (
> >    CHAR8                     *CommandLine;
> >    UINTN                     InitrdSize;
> >
> > +  //
> > +  // Redundant assignment to work around GCC48/GCC49 limitations.
> > +  //
> > +  CommandLine = NULL;
> > +
> >    //
> >    // Load the image. This should call back into the QEMU EFI loader file system.
> >    //
> >
>
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>

Pushed, thanks.