Hi Bastian, I've intentionally snipped much of your reply as I think we two agree on many of the aspects.
On Sun, May 12, 2024 at 07:35:09PM +0200, Bastian Blank wrote: > > 1. API expectation of *-$arch-cross packages > > I asked exactly that in > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1065416#55 I guess the best description is to be found in man dpkg-cross "Conversion process" and even that isn't entirely helpful. > > 4. cross-toolchain-base being bd-uninstallable > > Which directly correlates to undocumented Build-Conflicts in the > package. They neither show up in the changelog or the commit logs. > > > I don't exactly understand why it declares them, but I guess that > > having a different set of kernel headers available in > > /usr/$DEB_HOST_GNU_TYPE would cause them to be picked up by the build > > and potentially cause misbuilds. cross-toolchain-base builds these > > packages and it also uses them during build of glibc. > > So this reason is now gone. linux-source-* and linux-libc-dev are > similar enough in almost all cases. It's not gone as non-virtual linux-libc-dev-$arch-cross packages are still built from c-t-b. If c-t-b were to stop building them, I'd concur. > > 6. Cross bootstrap cannot tell whether linux-libc-dev supports an > > architecture > > Even in the past it could not. It could try to build the linux package > to see if it gets a working linux-libc-dev. Or have other code to hack > around, like changing the config. In the past, there was no need to tell. It would always build linux-libc-dev. Now that linux-libc-dev works for many but not all architectures, there is a need to tell. > Actually linux-libc-dev-$arch-cross is uncommunicated and uncoordinated > duplication of exactly the same content as linux-libc-dev. It is news to me that it is uncommunicated and uncoordinated, but that very accurately matches the rest of the disagreement. Yes, it is duplication. > 9. linux-libc-dev-*-cross provides incompatible headers to > build-essential > > Both linux-libc-dev and linux-libc-dev-*-cross provide the linux/* > includes that are used by the compiler but of different versions. It > is undefined if those can work with the (always older) asm/* provided > by linux-libc-dev-*-cross. Yes, this is a problem. It kinda is the same problem that we have with libc6-dev vs libc6-dev-$arch-cross and is why libc6-dev declares versioned breaks for libc6-dev-$arch-cross. > > 3. cross-toolchain-base could build a linux-libc-dev-cross package > > that Provides the earlier -$arch-cross packages and contains a > > similar symlink farm to linux-libc-dev. > > This requires coordination of the versions and strict enough > dependencies. So linux-libc-dev-cross would need to come out of the > same source as linux-libc-dev. Technically speaking, a linux-libc-dev-cross package could be built from c-t-b. It would just inherit all the other problems including your problem 9 from the previous approach and only address the space aspect. I listed it more for completeness sake than suggesting we actually go for this. > > 4. cross-toolchain-base could drop its Build-Conflicts. This may cause > > further problems though. > > Patch: https://bugs.debian.org/1067370#17 > > The build will now see multiple architectures of headers. So it needs > to handle this both for native (where build-conflicts can't be used > anyway) and cross the same. I don't understand what you are trying to say here. c-t-b only builds Arch:all packages, so the terms native and cross appear to not apply. Then again we also don't know what "further problems" are. I hope Matthias can shed some light here. > On Sun, May 12, 2024 at 01:53:33PM +0200, Helmut Grohne wrote: > > 2+3+6+7. linux-libc-dev could be split into linux-libc-dev-common > > arch:all m-a:foreign and the symlink farms could be kept in > > linux-libc-dev:any m-a:same retaining the size reduction. > > This would not actually work. linux-libc-dev-common would only contain > known architectures. So the current "change config, build > linux-libc-dev" will not longer work as well. This package would then > depend on a linux-libc-dev-common without the headers for this > architecture. I agree that it is not as simple as I pictured it. I was imagining that a m-a:same linux-libc-dev could simply contain all the architecture-dependent stuff. For many architectures that would practically work initially, but there is no bijective mapping between kernel architecture names and Debian architecture names, so for directories like /usr/lib/linux/uapi/arm is is unclear whether it should be part of linux-libc-dev:armel or linux-libc-dev:armhf or linux-libc-dev-common. Even for /usr/lib/linux/uapi/arm64, it is not clear whether that should be part of linux-libc-dev:arm64 or linux-libc-dev:musl-linux-arm64 or linux-libc-dev-common. You are implicitly resolving this to linux-libc-dev-common and conclude that headers would then go missing. We could now add another layer of indirection and add an arch:all binary package for every kernel architecture name, but that would go against the original goal of reducing size. Given this, I fear I concur with your "This would not actually work." Helmut
