[GSoC WIP] efi: create libacpi #1818

kpowkitty · 2025-08-21T08:30:14Z

GSoC WIP under @bsdimp

Description:

Refactored ACPICA for partial initialization in the loader.
This work is the preface for Lua bindings.

For our Lua bindings, we want to be able to walk the
ACPI namespace and evaluate objects. So, I've taken what
the kernel does in acpi_Startup() as a starting point,
and added the ACPI initialization for this. That includes
AcpiInitializeSubsystem, AcpiInitializeTables,
AcpiEnableSubsystem, and AcpiLoadTables. It is initialized
in reduced hardware mode with events enabled, to (1)
match what our Lua interface desires and (2) create a
smaller subset of ACPICA for the loader environment.

Notes:

acpi_detect() moved into libacpi.
Libacpi conditionally compiles ACPICA and glue code on amd64.
(arm64 will be addressed in a future update)
AcpiEnableSubsystem is initialized in reduced hardware mode,
but with events enabled. This is so that we do not need to pull
in all of ACPI_HARDWARE, but can evaluate objects.
Stubbed out Osd functions required for this limited initialization.
Conditionally exclude functions to make a minimal subset designed
around loader's/lua binding's needs:
- Exclude AcpiInitializeObjects, as we do not need this for walking
  the namespace and evaluating objects. (utxfinit.c)
- Exclude notify handlers or fixed event handlers. (evxface.c)
- Stub out print functions, as the loader does not have standard
  output. (osunixxf.c)
- Stub out AcpiOsSleep and AcpiOsGetTimer, as the loader is not
  multi-threaded and does not implement timers. (osunixxf.c)

Sponsored by: Google Summer of Code 2025
Signed-off-by: Kayla Powell (AKA Kat) [email protected]

github-actions · 2025-08-21T08:30:26Z

Thank you for taking the time to contribute to FreeBSD!
There is an issue that needs to be fixed:

Missing Signed-off-by lines^{b5d71ae, 8d354b3}

Please review CONTRIBUTING.md, then update and push your branch again.

stand/efi/acpica/acpi_detect.c

stand/efi/acpica/init_acpi.c

bsdimp · 2025-08-24T16:22:52Z

stand/efi/acpica/init_acpi.c

+	/* Initialize root tables. */
+	if (ACPI_FAILURE(status = acpi_Startup())) {
+		printf("ACPI: Startup failed with status %s\n", AcpiFormatException(status));
+		printf("ACPI: Try disabling either ACPI or apic support.\n");


this advice needs to be tailored to the loader.
And suggests we want a way to disable looking for ACPI which might be its own can of worms.

I opted to have method headers and minimal error message. Let me know if a more verbose error message is preferred.

stand/efi/loader/Makefile

bsdimp · 2025-08-24T16:24:46Z

stand/efi/contrib/dev/acpica/os_specific/service_layers/osunixxf.c

@@ -0,0 +1,1526 @@
+/******************************************************************************


I'll have to snag this diff, github's tool is useless for review.

bsdimp · 2025-08-24T16:27:06Z

sys/contrib/dev/acpica/include/acpixf.h

 * because ACPICA is fully compatible with other ACPI implementations.
 * Changing this will revert ACPICA (and machine ASL) to pre-OSI behavior.
 */
+#ifndef _STANDALONE


Why is this false for the loader?

Hmm.. So, when I first was building, I was consistently getting a null reference on the _OSI node when I was printing the ACPI namespace for debug in one of the ACPI routines. May be my own error. I did test that it compiles and runs without the interjected print statements, so I reverted this change. Let me know if we should keep it.

This work follows freebsd#1818.

Module for evaluating ACPI objects. Currently being tested. This work follows freebsd#1818.

Description: Refactored ACPICA for partial initialization in the loader. This work is the final preface for Lua bindings. Work on this commit involves: Subset ACPICA for loader land: For our Lua bindings, we need to be able to walk the ACPI namespace and evaluate objects. To do so, we need AcpiInitializeSubsystem, AcpiInitializeTables, AcpiEnableSubsystem, and AcpiLoadTables. Notes: -acpi_detect() moved into libacpi. -Libacpi conditionally compiles ACPICA and glue code on amd64. (arm64 will be addressed in a future update) -AcpiEnableSubsystem is initialized in reduced hardware mode, but with events enabled. This is so that we do not need to pull in all of ACPI_HARDWARE, but can evaluate objects. -Stubbed out Osd functions required for this limited initialization. -Conditionally exclude functions to make a minimal subset designed around loader's/lua binding's needs: --Exclude AcpiInitializeObjects, as we do not need this for walking the namespace and evaluating objects. (utxfinit.c) --Exclude notify handlers or fixed event handlers. (evxface.c) --Stub out print functions, as the loader does not have standard output. (osunixxf.c) --Stub out AcpiOsSleep and AcpiOsGetTimer, as the loader is not multi-threaded and does not implement timers. (osunixxf.c)

kpowkitty requested a review from bsdimp as a code owner August 21, 2025 08:30

kpowkitty force-pushed the acpi_init branch from 6ed6767 to f01aa4a Compare August 21, 2025 08:31

kpowkitty changed the title ~~[GSoC WIP] stand/efi: ACPICA in Loader~~ [GSoC WIP] stand/efi: ACPICA initialization Aug 21, 2025