[Buildroot] [PATCH 1/1] fs/common.mk: enable multithreaded xz compression
Peter Korsgaard
peter at korsgaard.com
Sun Jan 27 22:06:14 UTC 2019
>>>>> "Thomas" == Thomas Petazzoni <thomas.petazzoni at bootlin.com> writes:
> Hello,
> On Mon, 21 Jan 2019 18:39:24 +0100, Peter Korsgaard wrote:
>> > I thought it was using the version compiled by buildroot.
>> > Isn't that what host-xz is being used for?
>>
>> Yes, correct. Do you know if the -T 0 option generates identical output
>> as -T 1? Otherwise we may want to disable it for reproducible builds.
> Does it matter than the output of -T 0 and -T 1 are identical ?
It would cause an extra change in output between buildroot versions
using -T 0 and ones using -T 1 - But OK, probably that isn't really
important given all the other changes.
What I really meant was if the -T 1 option affected the output format,
and if so, if the difference involved any tradeoff (E.G. perhaps -T 1
compresses slightly worse than -T 0) and if repeated runs with -T 1
would generate the same output (on same machine or on another machine
with different number of threads).
> What matters for BR2_REPRODUCIBLE=y is if the same input, with -T 0,
> always provide the exact identical output.
With the new patch that only enables -T 1 for !reproducible builds,
that is correct.
--
Bye, Peter Korsgaard
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