[Mesa-dev] [Bug 100073] Shader Disk Cache 32/64 bit detection has a flaw. Missed existence of x32 ABI

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=100073

--- Comment #31 from oiaohm at gmail.com ---
(In reply to Emil Velikov from comment #28)
> Peter Dolding [seems like you like posting huge emails everywhere],
> attempting to summarise:
> 
> Debian's interpretation of "reproducible" is - _all_ the binaries across
> _any_ arch _must_ have the same build timestamp. Yet the documentation does
> not even remotely say so, even if [Debian people] they wrote it the first
> place.
> 
Its in the documentation just you have missed it.
https://reproducible-builds.org/docs/timestamps/
>>>The Debian reproducible builds effort proposed the SOURCE_DATE_EPOCH >>>environment variable to address the problem. Tools that support it1 will use >>>its value—a number of seconds since January 1st 1970, 00:00 UTC—instead of >>>the current date and time (when set). The variable has been formally defined >>>in the hope of wider adoption.

The lethal bit if you did not see it this time.
>>>instead of the current date and time (when set)
So you have no current date or time and they told you so in the documentation. 
So all files will be created with SOURCE_DATE_EPOCH because that is the current
date and time in the build.   So they set libfaketime to SOURCE_DATE_EPOCH.

So any system obeying reproducible build documentation to the letter file
timestamp is only going to tell you source code version roughly.  So if
SOURCE_DATE_EPOCH exists you might as well use your git submit version
information at least you will not be fooling yourself that it doing more than
what it is.

> Do I understand this correctly when I say that as you run the arm64 binary
> that will be used alongside arm64 Mesa - correct ? If so how can one use the
> arm64 build radeonsi alongside the x86 kernel amdgpu/radeon driver - kindly
> point us to a reading material.
> 
The process is straight forward on debian.
https://wiki.debian.org/QemuUserEmulation
apt-get install qemu binfmt-support qemu-user-static
To install and register qemu usermode for any elf binary the current kernel
cannot support directly.
https://wiki.debian.org/Multiarch/HOWTO
Then you just multiarch add arm64
dpkg --add-architecture arm64
update and install the arm64 userspace libraries and any programs you want as
arm64 by using :arm64 after it.

At that point you are ready to go and it currently just works that way
currently.

Debian does not bother about any special reading materials for it.  Same
process no matter the arch binaries you want to run.

So its really no different to adding i386 for 32 bit support other than having
to add the qemu usermode support.

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