vasilito
8d9f9e552f
Phase I.5: complete the acpid <-> kernel s2idle wire. After
MWAIT returns from an interrupt (typically an SCI from
acpid), the kernel now:
1. Clears S2IDLE_REQUESTED (via s2idle_request_clear)
2. Sets KSTOP_FLAG and triggers EVENT_READ on the kstop
handle (via s2idle_signal_wake)
This is the kernel-side analog of Linux 7.1
`acpi_s2idle_wake` in `drivers/acpi/sleep.c:758`. The
existing irq_trigger in generic_irq has already routed the
SCI to acpid's listener (which opened /scheme/irq/{sci}
earlier in the boot sequence), so the AML interpretation
is done by acpid asynchronously.
The s2idle flow now:
1. acpid: enter_s2idle() (\_TTS(0), \_PTS(0), \_SST(3))
2. acpid: write 's2idle\n' to /scheme/sys/kstop
-> kernel sets S2IDLE_REQUESTED, returns
3. Kernel idle path: mwait_loop() at deepest C-state
4. SCI breaks MWAIT (any interrupt, not just SCI)
5. Kernel mwait_loop post-handler (this commit):
- s2idle_request_clear()
- s2idle_signal_wake() -> KSTOP_FLAG set, EVENT_READ
6. acpid main loop: wakes from kstop handle read
7. acpid: exit_s2idle() (\_SST(2), \_WAK(0), \_SST(1))
The KSTOP_FLAG set in step 5 also serves as a 'reason'
indicator — acpid's CheckShutdown verb (kcall 2) returns
the flag, so acpid can distinguish a kstop-shutdown event
from a kstop-s2idle-wake event by polling CheckShutdown
after waking.
Hardware-agnostic: the same flow works for any platform
with Modern Standby firmware (Dell, HP, Lenovo, LG Gram,
etc.). The s2idle is the universal mechanism for low-power
idle; only the wake source (SCI, GPIO, RTC, ...) varies
per OEM.
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.
