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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.07.18 at 18:02, <roger.pau@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -168,6 +168,16 @@ $(TARGET).efi: ALT_BASE = 0x$(shell $(NM) 
> efi/relocs-dummy.o | sed -n 's, A ALT_
>  # Don't use $(wildcard ...) here - at least make 3.80 expands this too early!
>  $(TARGET).efi: guard = $(if $(shell echo efi/dis* | grep disabled),:)
>  
> +# Check if the build system supports PE.
> +efi := y$(shell rm -f efi/disabled)
> +efi := $(if $(efi),$(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c 
> efi/check.c -o efi/check.o 2>efi/disabled && echo y))
> +efi := $(if $(efi),$(shell $(LD) -mi386pep --subsystem=10 -o efi/check.efi 
> efi/check.o 2>efi/disabled && echo y))
> +efi := $(if $(efi),$(shell rm efi/disabled)y)
> +export BUILD_PE := $(efi)
> +ifeq ($(efi),y)
> +CFLAGS += -DBUILD_PE
> +endif

For one I'm not really happy about this being moved here: I did place it
in efi/Makefile for the simple reason of having as much as possible of
the EFI specifics in that single file.

Additionally I think it would be better if setting propagated through the
environment had XEN_ prefixes.

> --- a/xen/arch/x86/xen.lds.S
> +++ b/xen/arch/x86/xen.lds.S
> @@ -304,7 +304,9 @@ SECTIONS
>    } :text
>  #endif
>  
> -  efi = DEFINED(efi) ? efi : .;
> +#ifndef BUILD_PE
> +  efi = .;
> +#endif

And then I don't really understand how this is different from the
original #ifndef EFI that Daniel had problems with.

Jan



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