On 19.03.2025 14:40, Marek Marczykowski-Górecki wrote: > On Wed, Mar 19, 2025 at 01:43:59PM +0100, Jan Beulich wrote: >> On 19.03.2025 12:58, Marek Marczykowski-Górecki wrote: >>> On Wed, Mar 19, 2025 at 10:43:12AM +0100, Jan Beulich wrote: >>>> On 19.03.2025 10:15, Jan Beulich wrote: >>>>> On 18.03.2025 18:01, Marek Marczykowski-Górecki wrote: >>>>>> --- a/xen/Makefile >>>>>> +++ b/xen/Makefile >>>>>> @@ -411,6 +411,8 @@ ifneq ($(CONFIG_CC_IS_CLANG),y) >>>>>> CFLAGS += -Wa,--strip-local-absolute >>>>>> endif >>>>>> >>>>>> +$(call cc-option-add CFLAGS,CC,-ffile-prefix-map=$(XEN_ROOT)=.) >>>>> >>>>> This is lacking a comma: >>>>> >>>>> $(call cc-option-add,CFLAGS,CC,-ffile-prefix-map=$(XEN_ROOT)=.) >>>> >>>> And then, having tried the correct form (seeing the option then is passed >>>> to the compiler), I can't spot any difference in the resulting >>>> xen-syms.map. There were a few absolute paths there before (for >>>> arch/x86/x86_64/kexec_reloc.S and arch/x86/acpi/wakeup_prot.S), and the >>>> exact same ones are present afterwards. >>> >>> I'm not sure about xen-syms.map, it's about build path included in >>> xen-syms. It appears at least once in .debug_str and once in >>> .debug_line_str. >> >> In which case -fdebug-prefix-map= may suffice, which is available on >> more compiler versions? And then only if DEBUG_INFO=y? > > Oh, and xen.efi is full of build path. Binary on plain staging has 790 > occurrences. But there, -fdebug-prefix-map= also helps. > > But also I don't think -fdebug-prefix-map= will be enough for tools, it > looks like at least libxl has build path embedded in .rodata too.
And _all_ of them go away with -ffile-prefix-map=? >>> But also, I see the patch lost a chunk during rebase (from before >>> 4.17...), that adjusts XEN_ROOT to use $(realpath ...). That's the part >>> even mentioned in the commit message... >>> >>> I'll send v2 shortly. >> >> Provided there's actually a need. I was in fact wondering whether this >> was known to have significant effect prior to Anthony's work to make >> out-of-tree builds possible (plus less related adjustments), but may >> have lost most of its functionality since then (yet was still carried >> forward for all the time). > > There are clearly some build path embedding left. And > -ffile-prefix-map=/-fdebug-prefix-map= doesn't work correctly with > XEN_ROOT having xen/.. at the end. > BTW, would it be acceptable to have this? > > $(call cc-option-add,CFLAGS,CC,-fdebug-prefix-map=$(realpath > $(XEN_ROOT))=.) > > It may be less efficient (if make doesn't cache result), What do you mean here? Variable evaluation depends solely on how we use variables. I don't think there's any caching make does on its own? As to $(realpath ...) - make 3.80 doesn't support that. We do provide a fallback, but for that you need to use $(call realpath,...). Jan > but helps > especially in tools, where XEN_ROOT is set in _a lot_ of places. >
