Re: [PATCH 2/4] x86/hvmloader: Don't build as PIC/PIE

[Jan Beulich <jbeulich@xxxxxxxx>]

On 24.08.2022 12:59, Andrew Cooper wrote:
> HVMLoader is not relocatable in memory, and 32bit PIC code has a large
> overhead.  Build it as non-relocatable.
> 
> Bloat-o-meter reports a net:
>   add/remove: 0/0 grow/shrink: 3/107 up/down: 14/-3370 (-3356)
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Wei Liu <wl@xxxxxxx>
> ---
>  tools/firmware/hvmloader/Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/firmware/hvmloader/Makefile 
> b/tools/firmware/hvmloader/Makefile
> index 4f31c881613c..eb757819274b 100644
> --- a/tools/firmware/hvmloader/Makefile
> +++ b/tools/firmware/hvmloader/Makefile
> @@ -23,7 +23,8 @@ include $(XEN_ROOT)/tools/firmware/Rules.mk
>  # SMBIOS spec requires format mm/dd/yyyy
>  SMBIOS_REL_DATE ?= $(shell date +%m/%d/%Y)
>  
> -CFLAGS += $(CFLAGS_xeninclude)
> +CFLAGS += $(CFLAGS_xeninclude) -fno-pic
> +$(call cc-option-add,CFLAGS,-no-pie)

This is supposed to be coming from EMBEDDED_EXTRA_CFLAGS, if only
it was spelled correctly there. See the patch just sent. This line
(see that other patch) is meaningless anyway, as we don't use
$(CFLAGS) for linking here. So with it dropped
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

I do think though that the description could do with some expanding,
as I don't think -fpic or -fPIC is the default normally. I suppose
it's only specific distros which make this the default.

Jan