vasilito
5098d1651f
Reverts the prior session's -Z json-target-spec addition
that was breaking the build on nightly-2025-10-03 (the
kernel's rust-toolchain.toml specified toolchain). The
flag did not exist in that nightly; only nightly-2026-04-11
has it. Since the prior toolchain can build custom .json
target specs without any cargo-level gating (just pass
-Zunstable-options through -- separator to rustc),
the cleanest fix is to use rustc's -- directly:
cd SOURCE && cargo rustc -Z build-std=core,alloc ...
--bin kernel --target FILE --release
-- -C link-arg=...
RUSTUP_TOOLCHAIN=nightly-2025-10-03 is explicit so the
Makefile build works regardless of which toolchain the
outer shell has.
Also: restore rust-toolchain.toml to nightly-2025-10-03
(the version pinned in this fork). The 2026-04-01 bump
was a workaround attempt that did not work.
And: add .cargo/config.toml with [unstable]
json-target-spec = true as the new standard way (cargo
PR #16557) of enabling custom .json target specs. This
is harmless on older toolchains that don't have the feature
(cargo ignores unknown config keys).
Discovered via research into the nightly-2026-04-11 vs
nightly-2025-10-03 divergence after the redbear-mini build
failed with 'unknown -Z flag specified: json-target-spec'.
Kernel
Redox OS Microkernel
Requirements
nasmneeds to be available on the PATH at build time.
Building The Documentation
Use this command:
cargo doc --open --target x86_64-unknown-none
Debugging
QEMU
Running QEMU with the -s flag will set up QEMU to listen on port 1234 for a GDB client to connect to it. To debug the redox kernel run.
make qemu gdb=yes
This will start a virtual machine with and listen on port 1234 for a GDB or LLDB client.
GDB
If you are going to use GDB, run these commands to load debug symbols and connect to your running kernel:
(gdb) symbol-file build/kernel.sym
(gdb) target remote localhost:1234
LLDB
If you are going to use LLDB, run these commands to start debugging:
(lldb) target create -s build/kernel.sym build/kernel
(lldb) gdb-remote localhost:1234
After connecting to your kernel you can set some interesting breakpoints and continue
the process. See your debuggers man page for more information on useful commands to run.
Notes
-
Always use
foo.get(n)instead offoo[n]and try to cover for the possibility ofOption::None. Doing the regular way may work fine for applications, but never in the kernel. No possible panics should ever exist in kernel space, because then the whole OS would just stop working. -
If you receive a kernel panic in QEMU, use
pkill qemu-systemto kill the frozen QEMU process.
How To Contribute
To learn how to contribute to this system component you need to read the following document:
Development
To learn how to do development with this system component inside the Redox build system you need to read the Build System and Coding and Building pages.
How To Build
To build this system component you need to download the Redox build system, you can learn how to do it on the Building Redox page.
This is necessary because they only work with cross-compilation to a Redox virtual machine, but you can do some testing from Linux.
Funding - Unix-style Signals and Process Management
This project is funded through NGI Zero Core, a fund established by NLnet with financial support from the European Commission's Next Generation Internet program. Learn more at the NLnet project page.
