Connor-GH
8f468ec106
According to Agner Fog's documentation (https://agner.org/optimize/instruction_tables.pdf), the following information is true: These instructions have identical latency and throughput, except for Zen 5, which lists `test` as having reciprocal throughput of 0.25 cycles, and `bt` having reciprocal throughput of 0.33 cycles. This rules out the `bt` instruction for being the ideal instruction. The other `test` instructions were removed as candidates because, regardless of the size of the memory fetched at the address, at least 64 bytes will need to be fetched because it will be stored in the cache line. The WORD and DWORD cases can be ruled out because we cannot assume that `rsp + 16` or `rsp + 17` will not be on a 64-byte alignment boundary, which would cause two cachelines to be essentially filled with garbage we don't care about. The best case scenario is that we only need to fill one cache line with garbage, which is what the BYTE version does every time.
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.
