Re: [PATCH 6/8] x86/EFI: avoid use of GNU ld's --disable-reloc-section when possible

["Roger Pau Monné" <roger.pau@citrix.com>]

On Wed, Apr 21, 2021 at 05:34:29PM +0200, Jan Beulich wrote:
> On 21.04.2021 17:20, Roger Pau Monné wrote:
> > On Wed, Apr 21, 2021 at 02:03:49PM +0200, Jan Beulich wrote:
> >> On 21.04.2021 12:21, Roger Pau Monné wrote:
> >>> On Thu, Apr 01, 2021 at 11:46:44AM +0200, Jan Beulich wrote:
> >>>> @@ -189,7 +208,11 @@ EFI_LDFLAGS += --no-insert-timestamp
> >>>>  endif
> >>>>  
> >>>>  $(TARGET).efi: VIRT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A VIRT_START$$,,p')
> >>>> +ifeq ($(MKRELOC),:)
> >>>> +$(TARGET).efi: ALT_BASE :=
> >>>> +else
> >>>>  $(TARGET).efi: ALT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A ALT_START$$,,p')
> >>>
> >>> Could you maybe check whether $(relocs-dummy) is set as the condition
> >>> here and use it here instead of efi/relocs-dummy.o?
> >>
> >> I can use it in the ifeq() if you think that's neater (the current way
> >> is minimally shorter), but using it in the ALT_BASE assignment would
> >> make this differ more from the VIRT_BASE one, which I'd like to avoid.
> > 
> > Sorry, I think I'm slightly confused because when the linker can
> > produce the required relocations relocs-dummy variable is left empty,
> > so it won't be added to $(TARGET).efi.
> > 
> > But we still need to generate the efi/relocs-dummy.o file for the ELF
> > build I assume?
> 
> Not anymore (after "x86/EFI: redo .reloc section bounds determination").
> We need it, as said, to fish VIRT_BASE out of it. It indeed wouldn't get
> linked into any of the final binaries anymore.

Could you please add some text to the commit message to note that
while relocs-dummy is not linked into the final binary it's still
needed to get VIRT_BASE?

With that:

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

FWIW, it would also be nice to add some comments to the $(TARGET).efi
target commands, as it's quite impenetrable right now.

Thanks, Roger.