Feature request: improved build-id generation

[Laura Abbott]

On 03/19/2018 02:56 PM, Laura Abbott wrote:
> ArOn 03/16/2018 11:37 AM, Cary Coutant wrote:
>>>> Then I'm stating my case poorly.  I want a way to inject additional
>>>> data into the has computation.
>>>
>>> At one point, we proposed doing this via a linker- or assembler-oriented
>>> extra "salt" parameter, which would be hashed into the buildid.  This
>>> would most naturally be a n-v-r-a string, so the build is reproducible.
>>> Such a salt could be naturally injected via an environment variable set
>>> by rpmbuild.
>>>
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1002341 (salt!)
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1550152 (life without salt)
>>
>> I don't have a problem with adding a --build-id-salt="some arbitrary
>> string" option, and I think "salt" is exactly the right term for this.
>> I'd much prefer providing that than having you use a linker script.
>> (I'm somewhat puzzled that you find the linker script option less
>> objectionable than an object file with a note section.)
>>
>> As Nick said earlier, it's not that we don't care about your feature
>> request. I simply wanted to explore the options, and I gave you a
>> couple of options that require no new features at all.
>>
>> My other comments have been about the unnecessary conflating of a new
>> option like --build-id-salt with the choice of hashing algorithm.
>>
> 
> At least in the kernel we already have the infrastructure for
> customizations to linker scripts so it's fairly easy to expand on that.
> I have a prototype which should work, I just need to clean it up
> for review to see if it's feasible to merge vs. adding a --build-id-salt
> option.
> 

So while working through this and another packaging issue, I realized
another reason why we might just want the --build-id-salt option in
binutils. Because of how find-debuginfo.sh works, it finds and adds
debuginfo for all binary files in the buildroot. We have to package
several userspace utilities as part of the -devel package and those also
get their debug information extracted and packaged at the same time as
the rest of the kernel. The linker script trick doesn't work as easily.
I can potentially work around this in packaging or find a way to link all
userspace programs with an appropriate .o file but it's ugly. I'd much
rather just have a unified approach so that all binaries have an a appropriate
build-id.

Thanks,
Laura