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A comment on Guix Reduces Bootstrap Seed by Half. Parent comment

Re:Guix Reduces Bootstrap Seed by Half by thfuran on Wednesday October 09, 2019 @01:24PM (#21205466)
>If all of those rebuilt gccs are byte-for-byte the same

Isn't that pretty unlikely even if all the compilers are uncompromised?

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Re:Guix Reduces Bootstrap Seed by Half by delroth on Wednesday October 09, 2019 @01:41PM (#21205689)
No, that's what reproducible builds are all about: https://reproducible-builds.org/

Debian is currently sitting at around 93% of packages being reproducibly built. NixOS is close to 99% of the minimal install image set (https://r13y.com/).

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Re:Guix Reduces Bootstrap Seed by Half by tjoff on Wednesday October 09, 2019 @04:35PM (#21207739)
Reproducible builds don't mean compiling with different compilers, or even different versions of the same compiler, to result in the same binary.
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Re:Guix Reduces Bootstrap Seed by Half by comex on Wednesday October 09, 2019 @05:25PM (#21208280)
That's why you don't compare the GCC binaries built by different compilers. Instead, you use each of those GCC binaries (which may use different machine code but should implement the exact same functionality) to build another GCC, and you compare those binaries. That should result in identical binaries as long as GCC:

- is deterministic,

- does not invoke undefined behavior, and

- was correctly compiled by the original compilers.

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