Re: [Xen-devel] [PATCH v3 1/2] x86/efi: move the logic to detect PE build support

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Jul 25, 2018 at 02:48:28PM +0200, Daniel Kiper wrote:
> On Wed, Jul 18, 2018 at 12:27:32PM +0200, Roger Pau Monne wrote:
> > So that it can be used by other components apart from the efi specific
> > code. By moving the detection code creating a dummy efi/disabled file
> > can be avoided.
> >
> > This is required so that the conditional used to define the efi symbol
> > in the linker script can be removed and instead the definition of the
> > efi symbol can be guarded using the preprocessor.
> >
> > The motivation behind this change is to be able to build Xen using lld
> > (the LLVM linker), that at least on version 6.0.0 doesn't work
> > properly with a DEFINED being used in a conditional expression:
> >
> > ld    -melf_x86_64_fbsd  -T xen.lds -N prelink.o --build-id=sha1 \
> >     /root/src/xen/xen/common/symbols-dummy.o -o 
> > /root/src/xen/xen/.xen-syms.0
> > ld: error: xen.lds:233: symbol not found: efi
> >
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> This patch does more than subject says. So, please split this patch into
> 2 parts. One which really moves the detection logic and the second which
> replaces DEFINED() with #ifdef.

It's not possible to place the whole contents of the patch in a
subject line, that's why there's also a commit message that I think
correctly explains everything done in the patch.

IMO just having a patch to change the DEFINED to an ifdef is quite
pointless, it's better to switch it here together with the change that
actually introduces the define itself.

Thanks, Roger.

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