Re: [PATCH v2] x86/boot: Fix include paths for 32bit objects

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 03/09/2024 3:33 pm, Andrew Cooper wrote:
> On 03/09/2024 3:32 pm, Jan Beulich wrote:
>> On 03.09.2024 13:53, Andrew Cooper wrote:
>>> Most of Xen is build using -nostdinc and a fully specified include path.
>>> However, the makefile line:
>>>
>>>   $(head-bin-objs): XEN_CFLAGS := $(CFLAGS_x86_32) -fpic
>>>
>>> discards XEN_CFLAGS and replaces them with CFLAGS_x86_32.
>>>
>>> Reinstate -nostdinc, and copy all -I (and -Wa,-I) arguments from XEN_CFLAGS.
>> And the files in boot/ indeed need the -Wa,-I? I'd favor us not propagating
>> such without actually being required for a particular reason.
> Hmm ok fine, I'll strip that back out as both you and Roger have asked
> for it.
>
> I'm still waiting on Gitlab CI, so haven't pushed yet.

Eclair has just said no, because the -include is needed to pull in
Kconfig, ahead of compiler.h using CONFIG_GCC_* symbols

I'm retesting with:

@@ -14,10 +14,8 @@ $(obj)/head.o: $(head-bin-objs:.o=.bin)
 CFLAGS_x86_32 := $(subst -m64,-m32 -march=i686,$(XEN_TREEWIDE_CFLAGS))
 $(call cc-options-add,CFLAGS_x86_32,CC,$(EMBEDDED_EXTRA_CFLAGS))
 CFLAGS_x86_32 += -Werror -fno-builtin -g0 -msoft-float
-ifneq ($(abs_objtree),$(abs_srctree))
-CFLAGS_x86_32 += -I$(objtree)/include
-endif
-CFLAGS_x86_32 += -I$(srctree)/include
+CFLAGS_x86_32 += -nostdinc -include $(filter
%/include/xen/config.h,$(XEN_CFLAGS))
+CFLAGS_x86_32 += $(filter -I%,$(XEN_CFLAGS))
 
 # override for 32bit binaries
 $(head-bin-objs): CFLAGS_stack_boundary :=

which is the best I can think of to find the path of config.h in
XEN_CFLAGS.  This is the same pattern we use in filter-out elsewhere.

~Andrew