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Re: [PATCH] x86/EFI: suppress GNU ld 2.36'es creation of base relocs

On 22.02.2021 17:36, Andrew Cooper wrote:
> On 19/02/2021 08:09, Jan Beulich wrote:
>> --- a/xen/arch/x86/Makefile
>> +++ b/xen/arch/x86/Makefile
>> @@ -123,8 +123,13 @@ ifneq ($(efi-y),)
>>  # Check if the compiler supports the MS ABI.
>>  export XEN_BUILD_EFI := $(shell $(CC) $(XEN_CFLAGS) -c efi/check.c -o 
>> efi/check.o 2>/dev/null && echo y)
>>  # Check if the linker supports PE.
>> -XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) -mi386pep 
>> --subsystem=10 -S -o efi/check.efi efi/check.o 2>/dev/null && echo y))
>> +EFI_LDFLAGS = $(patsubst -m%,-mi386pep,$(XEN_LDFLAGS)) --subsystem=10 
>> --strip-debug
>> +XEN_BUILD_PE := $(if $(XEN_BUILD_EFI),$(shell $(LD) $(EFI_LDFLAGS) -o 
>> efi/check.efi efi/check.o 2>/dev/null && echo y))
>> +# Check if the linker produces fixups in PE by default (we need to disable 
>> it doing so for now).
>> +XEN_NO_PE_FIXUPS := $(if $(XEN_BUILD_EFI), \
>> +                         $(shell $(LD) $(EFI_LDFLAGS) 
>> --disable-reloc-section -o efi/check.efi efi/check.o 2>/dev/null && \
>> +                                 echo --disable-reloc-section))
> Why does --strip-debug move?

-S and --strip-debug are the same. I'm simply accumulating in
EFI_LDFLAGS all that's needed for the use in the probing construct.

Also I meanwhile have a patch to retain debug info, for which this
movement turns out to be a prereq. (I've yet to test that the
produced binary actually works, and what's more I first need to get
a couple of changes accepted into binutils for the linker to actually

> What's wrong with $(call ld-option ...) ?  Actually, lots of this block
> of code looks to be opencoding of standard constructs.

It looks like ld-option could indeed be used here (there are marginal
differences which are likely acceptable), despite its brief comment
talking of just "flag" (singular, plus not really covering e.g. input

- It working differently than cc-option makes it inconsistent to
  use (the setting of XEN_BUILD_EFI can't very well be switched to
  use cc-option); because of this I'm not surprised that we have
  only exactly one use right now in the tree.
- While XEN_BUILD_PE wants to be set to "y", for XEN_NO_PE_FIXUPS
  another transformation would then be necessary to translate "y"
  into "--disable-reloc-section".
- Do you really suggest to re-do this at this point in the release




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