[Buildroot] [PATCH] pkg-generic: suppress SOURCE_DATE_EPOCH warning in step_time

[Buildroot] [PATCH] pkg-generic: suppress SOURCE_DATE_EPOCH warning in step_time

[Nathan Bloch]

From: Nathan Bloch <nblochn@gmail.com>

The step_time hook calls date +%s.%N to measure build step elapsed time.
When SOURCE_DATE_EPOCH is set (for reproducible builds), GNU coreutils date
emits "Warning: using $SOURCE_DATE_EPOCH instead of true time" for every
call — twice per step, across all packages, resulting in hundreds of noisy
log lines.

Unset SOURCE_DATE_EPOCH inline for these timing-only calls, since they
measure real elapsed time and do not affect build reproducibility.

Signed-off-by: Nathan Bloch <nblochn@gmail.com>
---
 package/pkg-generic.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
index a2749320..e4bf6def 100644
--- a/package/pkg-generic.mk
+++ b/package/pkg-generic.mk
@@ -50,7 +50,7 @@ endef
 # Time steps
 define step_time
 	printf "%s:%-5.5s:%-20.20s: %s\n"           \
-	       "$$(date +%s.%N)" "$(1)" "$(2)" "$(3)"  \
+	       "$$(SOURCE_DATE_EPOCH= date +%s.%N)" "$(1)" "$(2)" "$(3)"  \
 	       >>"$(BUILD_DIR)/build-time.log"
 endef
 GLOBAL_INSTRUMENTATION_HOOKS += step_time
-- 
2.34.1

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Re: [Buildroot] [PATCH] pkg-generic: suppress SOURCE_DATE_EPOCH warning in step_time

[Arnout Vandecappelle via buildroot]

  Hi Nathan,

On 19/03/2026 11:42, Nathan Bloch wrote:
> From: Nathan Bloch <nblochn@gmail.com>
> 
> The step_time hook calls date +%s.%N to measure build step elapsed time.
> When SOURCE_DATE_EPOCH is set (for reproducible builds), GNU coreutils date
> emits "Warning: using $SOURCE_DATE_EPOCH instead of true time" for every
> call — twice per step, across all packages, resulting in hundreds of noisy
> log lines.

  I was going to apply but just to be sure I tested myself, and my (Fedora 43) 
GNU coreutils date turns out not to behave like that. So I went to the coreutils 
source and searched for SOURCE_DATE_EPOCH and for "instead of true time", and 
got no hits (except for the expected ones for SOURCE_DATE_EPOCH). It actually 
just uses true time. I also checked uutils and glibc just to be sure, found 
nothing there either.

  So it looks like you're using some patched version of GNU date. I'm not sure 
if it worth patching Buildroot to cater with that, unless you're on some pretty 
mainstream distro.

  Regards,
  Arnout

> Unset SOURCE_DATE_EPOCH inline for these timing-only calls, since they
> measure real elapsed time and do not affect build reproducibility.
> 
> Signed-off-by: Nathan Bloch <nblochn@gmail.com>
> ---
>   package/pkg-generic.mk | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
> index a2749320..e4bf6def 100644
> --- a/package/pkg-generic.mk
> +++ b/package/pkg-generic.mk
> @@ -50,7 +50,7 @@ endef
>   # Time steps
>   define step_time
>   	printf "%s:%-5.5s:%-20.20s: %s\n"           \
> -	       "$$(date +%s.%N)" "$(1)" "$(2)" "$(3)"  \
> +	       "$$(SOURCE_DATE_EPOCH= date +%s.%N)" "$(1)" "$(2)" "$(3)"  \
>   	       >>"$(BUILD_DIR)/build-time.log"
>   endef
>   GLOBAL_INSTRUMENTATION_HOOKS += step_time

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Re: [Buildroot] [PATCH] pkg-generic: suppress SOURCE_DATE_EPOCH warning in step_time

[Nicolas Cavallari]

On 4/7/26 20:42, Arnout Vandecappelle via buildroot wrote:
>   Hi Nathan,
> 
> On 19/03/2026 11:42, Nathan Bloch wrote:
>> From: Nathan Bloch <nblochn@gmail.com>
>>
>> The step_time hook calls date +%s.%N to measure build step elapsed time.
>> When SOURCE_DATE_EPOCH is set (for reproducible builds), GNU coreutils 
>> date
>> emits "Warning: using $SOURCE_DATE_EPOCH instead of true time" for every
>> call — twice per step, across all packages, resulting in hundreds of 
>> noisy
>> log lines.
> 
>   I was going to apply but just to be sure I tested myself, and my 
> (Fedora 43) GNU coreutils date turns out not to behave like that. So I 
> went to the coreutils source and searched for SOURCE_DATE_EPOCH and for 
> "instead of true time", and got no hits (except for the expected ones 
> for SOURCE_DATE_EPOCH). It actually just uses true time. I also checked 
> uutils and glibc just to be sure, found nothing there either.
> 
>   So it looks like you're using some patched version of GNU date. I'm 
> not sure if it worth patching Buildroot to cater with that, unless 
> you're on some pretty mainstream distro.

You need to enable BR2_REPRODUCIBLE to have package/fakedate/fakedate 
installed as host/bin/date to obey SOURCE_DATE_EPOCH.
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Re: [Buildroot] [PATCH] pkg-generic: suppress SOURCE_DATE_EPOCH warning in step_time

[Arnout Vandecappelle via buildroot]

On 08/04/2026 11:29, Nicolas Cavallari wrote:
> On 4/7/26 20:42, Arnout Vandecappelle via buildroot wrote:
>>   Hi Nathan,
>>
>> On 19/03/2026 11:42, Nathan Bloch wrote:
>>> From: Nathan Bloch <nblochn@gmail.com>
>>>
>>> The step_time hook calls date +%s.%N to measure build step elapsed time.
>>> When SOURCE_DATE_EPOCH is set (for reproducible builds), GNU coreutils date
>>> emits "Warning: using $SOURCE_DATE_EPOCH instead of true time" for every
>>> call — twice per step, across all packages, resulting in hundreds of noisy
>>> log lines.
>>
>>   I was going to apply but just to be sure I tested myself, and my (Fedora 43) 
>> GNU coreutils date turns out not to behave like that. So I went to the 
>> coreutils source and searched for SOURCE_DATE_EPOCH and for "instead of true 
>> time", and got no hits (except for the expected ones for SOURCE_DATE_EPOCH). 
>> It actually just uses true time. I also checked uutils and glibc just to be 
>> sure, found nothing there either.
>>
>>   So it looks like you're using some patched version of GNU date. I'm not sure 
>> if it worth patching Buildroot to cater with that, unless you're on some 
>> pretty mainstream distro.
> 
> You need to enable BR2_REPRODUCIBLE to have package/fakedate/fakedate installed 
> as host/bin/date to obey SOURCE_DATE_EPOCH.

  D'oh, I missed that.

  However, how come host/bin/date gets used in the timing step? $(HOST_DIR)/bin 
doesn't get exported to PATH, so it should only get used in the actual build and 
configure steps (which use PATH=$(BR_PATH)).

  I tried it locally (with BR2_REPRODUCIBLE=y obviously) and I don't see this issue.

  Regards,
  Arnout


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