2 ms·

Why can't the packages be cross-compiled on a platform with reasonable performance?

pabs3 2y ago
The experience of the Debian folks working on cross-compiling is that ~50% of packages are cross-compilable, and that was only achieved with a lot of work and a lot of patches merged. Also, it regresses quite a lot. https://crossqa.debian.net/ https://crossqa.debian.net/
ahoka 2y ago
Not everything can be easily cross compiled, unfortunately.
- boredatoms 2y ago
  Its also just plain annoying to configure in many cases
rwmj 2y ago
There's a lot of cases where you want to build something and run it afterwards, such as tests or intermediate tooling used in later steps in the build. In any case, I actually want to use RISC-V machines for my development environment.
fweimer 2y ago
The goal is to actually run RISC-V binaries on RISC-V hardware, to see what works and what doesn't. You wouldn't spot code generations bugs like this one if you merely cross-compile and never run the binaries: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=c65046ff2ef0a9a46e59bc0b3369b2d226f6a239 https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=c65046ff2e... For quite some time to come, the main user of the Fedora riscv64 port will be the Fedora riscv64 builders. With cross-compilation, we wouldn't even have that limited use of the binaries produced.
brucehoult 2y ago
Many or most packages don't have good cross-build infrastructure. That's important when you're a Fedora or Ubuntu building 50k+ random packages, not just working on GCC / LLVM / Linux Kernel all the time. Doing "native" build in an emulator works for just about everything, but with a 10x - 15x slowdown compared to native or cross-build. While price/performance of RISC-V is currently significantly worse than x86, it's not 10x worse. A $2500 Milk-V Pioneer (64 cores, 128 GB RAM) builds a RISC-V Linux kernel five times faster than a $1500 x86 laptop (24 cores) using RISC-V docker/qemu. A $75 VisionFive 2 or BPI-F3 takes 3 times longer than the x86 with qemu but costs 20 times less. If you're only building one thing at a time and already have the fast x86 ... then, sure, use that. But if you want a build farm then RISC-V native on either the Pioneer or the VF2 is already much better. These P550 machines are an incremental improvement again, in price/performance. For more numbers see: https://news.ycombinator.com/item?id=42395796 https://news.ycombinator.com/item?id=42395796

The experience of the Debian folks working on cross-compiling is that ~50% of packages are cross-compilable, and that was only achieved with a lot of work and a lot of patches merged. Also, it regresses quite a lot. https://crossqa.debian.net/ https://crossqa.debian.net/

ahoka 2y ago

Not everything can be easily cross compiled, unfortunately.

boredatoms 2y ago
Its also just plain annoying to configure in many cases

rwmj 2y ago

There's a lot of cases where you want to build something and run it afterwards, such as tests or intermediate tooling used in later steps in the build. In any case, I actually want to use RISC-V machines for my development environment.

fweimer 2y ago

The goal is to actually run RISC-V binaries on RISC-V hardware, to see what works and what doesn't. You wouldn't spot code generations bugs like this one if you merely cross-compile and never run the binaries: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=c65046ff2ef0a9a46e59bc0b3369b2d226f6a239 https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=c65046ff2e... For quite some time to come, the main user of the Fedora riscv64 port will be the Fedora riscv64 builders. With cross-compilation, we wouldn't even have that limited use of the binaries produced.

brucehoult 2y ago

Many or most packages don't have good cross-build infrastructure. That's important when you're a Fedora or Ubuntu building 50k+ random packages, not just working on GCC / LLVM / Linux Kernel all the time. Doing "native" build in an emulator works for just about everything, but with a 10x - 15x slowdown compared to native or cross-build. While price/performance of RISC-V is currently significantly worse than x86, it's not 10x worse. A $2500 Milk-V Pioneer (64 cores, 128 GB RAM) builds a RISC-V Linux kernel five times faster than a $1500 x86 laptop (24 cores) using RISC-V docker/qemu. A $75 VisionFive 2 or BPI-F3 takes 3 times longer than the x86 with qemu but costs 20 times less. If you're only building one thing at a time and already have the fast x86 ... then, sure, use that. But if you want a build farm then RISC-V native on either the Pioneer or the VF2 is already much better. These P550 machines are an incremental improvement again, in price/performance. For more numbers see: https://news.ycombinator.com/item?id=42395796 https://news.ycombinator.com/item?id=42395796