Re: [Xen-devel] [PATCH v2] xen/x86: fix linker script to work with lld

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

On Wed, Jul 11, 2018 at 12:42:48PM +0200, Daniel Kiper wrote:
> On Wed, Jul 11, 2018 at 12:25:21PM +0200, Roger Pau Monne wrote:
> > lld (the llvm linker) has some issues with Xen linker script. It
> > doesn't understand '||' in assert expressions:
> >
> > 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:260: malformed number: |
> > >>> ASSERT(__image_base__ > (((((((((261 >> 8) * 0xffff000000000000) | (261 
> > >>> << 39))) + ((1 << 39) / 2)) + (64 << 30)) + (1 << 30)) + (1 << 30))) ||
> > >>>                                                                         
> > >>>                                                                       ^
> >
> > And doesn't work properly with the 'DEFINED(foo) ? foo : ...'
> > 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
> >
> > Fix the first issue by using '|' instead of '||', and the second one
> > by declaring the efi symbol as a weak symbol.
> >
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > ---
> > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > Cc: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> > ---
> > Changes since v1:
> >  - Export efi as a weak symbol in order to remove the DEFINED
> >    conditional in the linker script.
> >  - Add a define for setting the weak attribute and replace existing
> >    users.
> 
> May I ask you to split this patch into two separate patches?
> One for __weak change and one for DEFINED() drop please.

So to introduce and use __weak also for the efi variable and then drop
the DEFINED in a following patch?

Or switch efi to use __weak in the same patch where DEFINED is
dropped?

Roger.

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