vasilito
1c870c06ec
cargo 1.98.0-dev (4d1f98451 2026-05-15) requires -Zunstable-options to be passed to cargo itself (not just rustc) to accept a custom target spec. Without it, the kernel Makefile fails with: error: error loading target specification: custom targets are unstable and require `-Zunstable-options` The Makefile already had -Z build-std, -Zbuild-std-features, and -Z json-target-spec (which are passed to rustc), but the top-level cargo invocation needed -Zunstable-options to accept the target. This is required by both nightly-2025-10-03 (the kernel fork rust-toolchain) and nightly-2026-04-01 (the host default). On the cookbook (redoxer-1.0 toolchain), the error is the same because -Zunstable-options is a separate cargo-level flag from the rustc-level -Z flags. Discovered when attempting to build redbear-mini after the 0.2.5 fork was created from 0.2.4. The Makefile worked on 0.2.4 because the prior kernel cook used a cached build; the 0.2.5 build started fresh and hit the error.
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.
