Re: [PATCH] x86/boot: Reinstate -nostdinc for CFLAGS_x86_32

[Anthony PERARD <anthony.perard@vates.tech>]

On Tue, Sep 03, 2024 at 11:49:40AM +0100, 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 add the arch include path to the command line.  This
> is a latent bug for now, but it breaks properly with subsequent include
> changes.
> 
> Fixes: d58a509e01c4 ("build,x86: remove the need for build32.mk")

I disagree with this. I'm pretty sure I've check that no command line
have changed.

Also, this commit shows that CFLAGS was only coming from root's
Config.mk:
> diff --git a/xen/arch/x86/boot/build32.mk b/xen/arch/x86/boot
> deleted file mode 100644
> index e90680cd9f..0000000000
> --- a/xen/arch/x86/boot/build32.mk
> +++ /dev/null
> @@ -1,40 +0,0 @@
> -override XEN_TARGET_ARCH=x86_32
> -CFLAGS =
> -include $(XEN_ROOT)/Config.mk

So, I'm pretty sure, -nostdinc was never used before. But happy to be
told that I've come to the wrong conclusion. (We would need to check by
building with an old version without this commit to be sure.)

"xen/arch/x86/boot" as it's own sets of CFLAGS, which is annoying and I
haven't really tried to change that. This is also why XEN_CFLAGS is been
discarded.

Cheers,

-- 

Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech