Re: [PATCH] symbols: explicitly specify source file name for symtab

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.05.2026 11:20, Roger Pau Monné wrote:
> On Mon, May 11, 2026 at 12:00:03PM +0200, Jan Beulich wrote:
>> If there are any local symbols in an object file, GNU ld will create an
>> STT_FILE symbol derived from the object file name if there is none in the
>> incoming symbol table. The object file name, however, varies between
>> linking passes. As a result, symbol name compression can yield different
>> results if any of those local symbols need retaining (Arm [and RISC-V]
>> mapping symbols are omitted, for example). If that difference in
>> compression would yield a difference in the sizes of symbol_names[] or
>> symbols_token_table[], the compare-symbol-tables sanity check will fail.
>>
>> Fixes: d37d63d4b548 ("symbols: prefix static symbols with their source file 
>> names")
>> Reported-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks.

>> --- a/xen/arch/x86/Makefile
>> +++ b/xen/arch/x86/Makefile
>> @@ -200,7 +200,8 @@ $(TARGET).efi: $(objtree)/prelink.o $(no
>>  ifeq ($(CONFIG_DEBUG_INFO),y)
>>      $(if $(filter --strip-debug,$(EFI_LDFLAGS)),echo,:) "Will strip debug 
>> info from $(@F)"
>>  endif
>> -    $(objtree)/tools/symbols $(all_symbols) --empty > $(dot-target).0s.S
>> +    $(objtree)/tools/symbols $(all_symbols) --source-name=$(@F).S --empty \
>> +            > $(dot-target).0s.S
>>      $(MAKE) $(build)=$(@D) .$(@F).0s.o
>>      $(foreach base, $(VIRT_BASE) $(ALT_BASE), \
>>                $(LD) $(call EFI_LDFLAGS,$(base)) -T $(obj)/efi.lds $< 
>> $(relocs-dummy) \
>> @@ -210,6 +211,7 @@ endif
>>              > $(dot-target).1r.S
>>      $(NM) -pa --format=sysv $(dot-target).$(VIRT_BASE).0 \
>>              | $(objtree)/tools/symbols $(all_symbols) --sysv --sort \
>> +                  --source-name=$(@F).S \
>>              > $(dot-target).1s.S
>>      $(MAKE) $(build)=$(@D) .$(@F).1r.o .$(@F).1s.o
>>      $(foreach base, $(VIRT_BASE) $(ALT_BASE), \
>> @@ -220,6 +222,7 @@ endif
>>              > $(dot-target).2r.S
>>      $(NM) -pa --format=sysv $(dot-target).$(VIRT_BASE).1 \
>>              | $(objtree)/tools/symbols $(all_symbols) --sysv --sort \
>> +                  --source-name=$(@F).S \
>>              > $(dot-target).2s.S
> 
> Wouldn't it be more accurate to use $(dot-target) as the source name?
> 
> Maybe $(notdir $(dot-target)).S?

Why would that be better (more accurate)? The file names change, so the
specified file is "virtual" anyway. I simply don't see why prepending a
. would be helpful.

> I see the default is already set to the target filename for other
> arches, so not a big deal IMO.

It's a "virtual" filename also there. No real xen-syms.S is ever created.

Jan