On 07/31/2018 12:06 AM, Adam Borowski wrote: > On Mon, Jul 30, 2018 at 11:18:16PM +0200, John Paul Adrian Glaubitz wrote: >>> On Jul 30, 2018, at 10:42 PM, Adam Borowski <[email protected]> wrote: >>> >>> Also, this machine does have neon so it's not even armhf baseline. And so >>> many packages compile but don't test. Thus, regressions from building on >>> arm64 need not just hardware but also manpowers to detect. >> >> But why should compiling ARMv7 on ARMv8 automatically change the baseline >> when it’s actually a hardwired configure option in gcc? > > There's way too many packages that do compile-time detection.
Why has it never been an issue with PowerPC on PowerPC64 kernels, SPARC on SPARC64 kernels, ARMv5 on ARMv7 kernels, MIPSEL on MIPS64EL kernels, i386 on amd64 kernels and so on. It's not the first time at all that we're building with a 32-bit userland on 64-bit kernels. >> By the same logic, lots of the packages we build on ARMv7 machines for >> armel wouldn’t work on ARMv5. > > And many probably don't, but such gear is so weak that a good part of > packages simply have no one running them. I disagree. Previous experience with other architectures as shown above shows that it does work. >> Plus, we can build on the experience that openSUSE made with building >> ARMv6/7 on ARMv8. Why are we ignoring that? > > How do you propose to do that other than sometimes digging through their > packaging for a patch here and there? SUSE is upstreaming usually everything. Also, I talked to Alex Graf who is in charge of these things at SUSE and he confirmed me that building of ARMv7 on ARMv8 is possible. He's also the one who fixed QEMU-KVM issues with ARMv7 on ARMv8. Oh, and SUSE also does extensive testing in OpenQA to make sure the compiled packages actually work. So, I really think we can be confident that building 32-bit ARM packages on 64-bit machines will actually work the same way it does and did in the past for other architectures. If you find a counter-example, I'd be very interested to learn about it, I love finding new bugs after all :-). Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer - [email protected] `. `' Freie Universitaet Berlin - [email protected] `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
