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

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Wed, Jul 11, 2018 at 01:46:56PM +0200, Roger Pau Monné wrote:
> 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?

The latter please.

Daniel

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