Re: [PATCH] tools/build: make in-target rule robust against too long argument error

[Changqing Li <changqing.li@windriver.com>]

On 8/19/25 04:38, Ian Rogers wrote:
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> On Mon, Jul 28, 2025 at 2:31 AM <changqing.li@windriver.com> wrote:
>> From: Changqing Li <changqing.li@windriver.com>
>>
>> The command length of in-target scales with the depth of the directory
>> times the number of objects in the Makefile. When there are many
>> objects, and O=[absolute_path] is set, and the absolute_path is
>> relatively long. It is possile that this line "$(call
>> if_changed,$(host)ld_multi)" will report error:
>> "make[4]: /bin/sh: Argument list too long"
>>
>> For example, build perf tools with O=/long/output/path
>>
>> Like built-in.a and *.mod rules in scripts/Makefile.build, add
>> $(objpredix)/ by the shell command instead of by Make's builtin
>> function.
>>
>> Signed-off-by: Changqing Li <changqing.li@windriver.com>
> Thanks Changqing, the change makes sense to me. The printf is pushing
> the values into xargs rather than using $^ with ld. I've tried
> reproducing the error to test your fix by creating long directory
> names in /tmp and then passing them to O=. I've not been able to do
> this. Could you send a reproduction for me to test?
>
> Thanks,
> Ian

Hi, Ian

Thanks. Here is my steps:

1. git clone https://github.com/torvalds/linux.git

2. cd linux/tools/perf/

3. mkdir 
/tmp/01234567890123456789/0123456789012345678901234567890123456789/0123456789012345678901234567890123456789/012345678901234567890123456789/01234567890123456789/012345678901234567890123456789/01234567890123456789012345678/9012345678901234567890123456789/012345678901234567890123456789/012345678901234567890123456789/01234567890123456789012345678901234567890123456789012345678901234567890123/perf-1.0

4.  make NO_LIBTRACEEVENT=1 
O=/tmp/01234567890123456789/0123456789012345678901234567890123456789/0123456789012345678901234567890123456789/012345678901234567890123456789/01234567890123456789/012345678901234567890123456789/01234567890123456789012345678/9012345678901234567890123456789/012345678901234567890123456789/012345678901234567890123456789/01234567890123456789012345678901234567890123456789012345678901234567890123/perf-1.0 


5. Above step failed with error:

make[4]: /bin/sh: Argument list too long

make[4]: *** [/buildarea2/cli10/tmp/linux/tools/build/Makefile.build 
<https://urldefense.com/v3/__http://Makefile.build__;!!AjveYdw8EvQ!c2n7zPX4Vrhwd7a9UxsjCXBGO5V8Llmon1egvupz4kHL4869ilesQgRgQZO8nj8AWwQJUlY9DOoWPD688quA73jNugR6IZRxy09Eig$>:148: 
/tmp/01234567890123456789/0123456789012345678901234567890123456789/0123456789012345678901234567890123456789/012345678901234567890123456789/01234567890123456789/012345678901234567890123456789/01234567890123456789012345678/9012345678901234567890123456789/012345678901234567890123456789/012345678901234567890123456789/01234567890123456789012345678901234567890123456789012345678901234567890123/perf-1.0/util/perf-util-in.o] 
Error 127

make[3]: *** [/buildarea2/cli10/tmp/linux/tools/build/Makefile.build 
<https://urldefense.com/v3/__http://Makefile.build__;!!AjveYdw8EvQ!c2n7zPX4Vrhwd7a9UxsjCXBGO5V8Llmon1egvupz4kHL4869ilesQgRgQZO8nj8AWwQJUlY9DOoWPD688quA73jNugR6IZRxy09Eig$>:142: 
util] Error 2

make[2]: *** [Makefile.perf:797: 
/tmp/01234567890123456789/0123456789012345678901234567890123456789/0123456789012345678901234567890123456789/012345678901234567890123456789/01234567890123456789/012345678901234567890123456789/01234567890123456789012345678/9012345678901234567890123456789/012345678901234567890123456789/012345678901234567890123456789/01234567890123456789012345678901234567890123456789012345678901234567890123/perf-1.0/perf-util-in.o] 
Error 2


Regards

Changqing
>> ---
>>   tools/build/Makefile.build | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/build/Makefile.build b/tools/build/Makefile.build
>> index 3584ff308607..39066a3ef2fc 100644
>> --- a/tools/build/Makefile.build
>> +++ b/tools/build/Makefile.build
>> @@ -70,11 +70,13 @@ quiet_cmd_gen = GEN     $@
>>   # If there's nothing to link, create empty $@ object.
>>   quiet_cmd_ld_multi = LD      $@
>>         cmd_ld_multi = $(if $(strip $(obj-y)),\
>> -                     $(LD) -r -o $@  $(filter $(obj-y),$^),rm -f $@; $(AR) rcs $@)
>> +                     printf "$(objprefix)%s " $(patsubst $(objprefix)%,%,$(filter $(obj-y),$^)) | \
>> +                     xargs $(LD) -r -o $@,rm -f $@; $(AR) rcs $@)
>>
>>   quiet_cmd_host_ld_multi = HOSTLD  $@
>>         cmd_host_ld_multi = $(if $(strip $(obj-y)),\
>> -                          $(HOSTLD) -r -o $@  $(filter $(obj-y),$^),rm -f $@; $(HOSTAR) rcs $@)
>> +                          printf "$(objprefix)%s " $(patsubst $(objprefix)%,%,$(filter $(obj-y),$^)) | \
>> +                          xargs $(HOSTLD) -r -o $@,rm -f $@; $(HOSTAR) rcs $@)
>>
>>   ifneq ($(filter $(obj),$(hostprogs)),)
>>     host = host_
>> --
>> 2.34.1
>>