 | NixOS RISC-V | 235 Members |
| NixOS on RISC-V https://wiki.nixos.org/wiki/RISC-V https://pad.lassul.us/NixOS-riscv64-linux https://github.com/orgs/NixOS/teams/risc-v | 69 Servers |
| NixOS RISC-V | 235 Members |
| NixOS on RISC-V https://wiki.nixos.org/wiki/RISC-V https://pad.lassul.us/NixOS-riscv64-linux https://github.com/orgs/NixOS/teams/risc-v | 69 Servers |
| Sender | Message | Time |
|---|---|---|
| 10 Apr 2026 | ||
 GenericNerdyUsername | How much effort would it be to remove the DF requirement or do them in software? | 12:40:32 |
 cleverca22 | basically, this macro will generate 2 different opcodes, and update a table with the address, so other code can patch things at bootup | 12:40:52 |
 Alex | In reply to @genericnerdyusername:matrix.orgIt's not a requirement, just what most toolchains assume. I think you could probably get away with I_Zicsr for a simple single-core bare metal program.It would entirely depend on what program you're looking to run. | 12:42:11 |
| cleverca22 | in this case, it can either be a | 12:42:31 |
| cleverca22 | it defaults to the nop case i believe | 12:42:42 |
| GenericNerdyUsername | The end goal is booting a minimal nixos install and running some neofetch derivative | 12:42:57 |
| Alex | In reply to @genericnerdyusername:matrix.orgYou can try different ISAs by setting gcc.arch.My suggestion: try IMA_Zicsr_Zifencei (you might not need to specify the Zi instructions with GCC) | 12:44:10 |
| GenericNerdyUsername | Set that where? | 12:45:26 |
| cleverca22 | arch/riscv/include/asm/alternative-macros.hreading more, i can see it will generate the first opcode, nop, and force it to not be compressed (so both options are 32bits)then it will use an assembly .if statement gated on the config flag, to maybe push the 2nd opcode into the .alternative section of the binary, along with some offsets to the nop | 12:45:26 |
| cleverca22 | oh, but i also see things now gated by CONFIG_RISCV_ALTERNATIVE, hmmmm? | 12:49:04 |
| cleverca22 | ah, when CONFIG_RISCV_ALTERNATIVE=n it just doesnt support the extensions at all, and always goes with the non-zbb case (in the strcmp example) | 12:49:51 |
| cleverca22 | https://github.com/torvalds/linux/blob/master/arch/riscv/Kconfig#L542-L555 | 12:51:54 |
 josw left the room. | 16:46:54 | |
| 13 Apr 2026 | ||
 Pol changed their display name from Slushee to Pol. | 14:16:53 | |
| 15 Apr 2026 | ||
 @98765abc:mozilla.org left the room. | 06:49:36 | |
 zoë (she/her) joined the room. | 09:38:46 | |
| zoë (she/her) | i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.mkShell/stdenv with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain instead of an x86->rv32 one... where's the problem with my mental model, and how can i get a shell with the right environment? | 09:46:07 |
| zoë (she/her) | i used this article and this one as sources, but I guess I might have missed or misunderstood something? | 09:47:22 |
| zoë (she/her) | * i used this article and this one as sources, but I guess I might h](https://www.hobson.space/posts/nixcross/)ave missed or misunderstood something? | 09:47:47 |
| zoë (she/her) | * i used this article and this one as sources, but I guess I might have missed or misunderstood something? | 09:48:05 |
| zoë (she/her) | * i used this article and this one as sources, but I guess I must have missed or misunderstood something? | 09:48:14 |
| zoë (she/her) | * i used this article and this one as sources, but I guess I must have missed or misunderstood something? | 09:49:44 |
| zoë (she/her) | * i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.mkShell/stdenv with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain, and if i do nix-shell -E '(import <nixpkgs> {}).pkgsCross.riscv32.mkShell {} and try to compile a simple program, I get a cc1: execvp: no such file or directory error... where's the problem with my mental model, and how can i get a shell with the right environment? | 09:54:19 |
| zoë (she/her) | * i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.mkShell/stdenv with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain, and if i do nix-shell -E '(import <nixpkgs> {}).pkgsCross.riscv32.mkShell {}' and try to compile a simple program, I get a cc1: execvp: no such file or directory error... where's the problem with my mental model, and how can i get a shell with the right environment? | 09:59:49 |
| zoë (she/her) | * i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.mkShell/stdenv with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain (which cc points to a nix-managed gcc, but for x86)... where's the problem with my mental model, and how can i get a shell with the right environment? | 10:01:19 |
| zoë (she/her) | * i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.stdenv/mkShell with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain (which cc points to a nix-managed gcc, but for x86)... where's the problem with my mental model, and how can i get a shell/derivation environment with the right toolchain? | 10:12:44 |
| zoë (she/her) | * i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.stdenv/mkShell with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain (which cc points to a nix-managed gcc, but for x86)... where's the problem with my mental model, and how can i get a shell/derivation environment with the right toolchain?(ideally i'd also like to get an llvm-based toolchain, but that seems like it's basically completely unsupported) | 10:14:20 |
| zoë (she/her) | * i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.stdenv/mkShell with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain (which cc points to a nix-managed gcc, but for x86)... where's the problem with my mental model, and how can i get a shell/derivation environment with the right toolchain?(ideally i'd also like to get an llvm-based toolchain, but that seems like it's basically completely unsupported ;-;) | 10:14:27 |
| zoë (she/her) | * i'm not sure if this is the right place to ask, especially because this is a very noob question, but i'm trying to get a shell for doing cross-compilation from x86 to riscv. I thought it'd be a simple matter of getting a pkgsCross.riscv32.stdenv/mkShell with the right nativeBuildInputs etc, but if i do nix-shell -p pkgsCross.riscv32.stdenv, I just get an x86->x86 toolchain (which cc points to a nix-managed gcc, but for x86)... where's the problem with my mental model, and how can i get a shell/derivation environment with the right toolchain?(ideally i'd also like to get an llvm-based toolchain, but that seems like it's basically completely unsupported ;-; i mean, compiler-rt-libc-riscv32-unknown-linux-gnu is broken so...) | 10:15:21 |
| zoë (she/her) | hmm, i might just be dumb... i though that .stdenv was basically just like an empty mkDerivation { } but I guess notalso i got confused by mkShell having which cc point to my system's cc, but actually $CC is correct it seems. it's just going to be annoying since some of the stuff i want to use has cc in its makefiles instead of $CC | 10:21:25 |