Remove ACPI from the TODO list and add a new section to document current ACPI support in U-Boot.
Signed-off-by: Bin Meng bmeng.cn@gmail.com
---
Changes in v2: - Update ACPI support status in more details: what's supported, what's not supported, what's optional.
doc/README.x86 | 44 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-)
diff --git a/doc/README.x86 b/doc/README.x86 index 732d375..ce806ee 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -958,12 +958,52 @@ transformations. Remember to add attribution to coreboot for new files added to U-Boot. This should go at the top of each file and list the coreboot filename where the code originated.
+ACPI Support Status +------------------- +Advanced Configuration and Power Interface (ACPI) [16] aims to establish +industry-standard interfaces enabling OS-directed configuration, power +management, and thermal management of mobile, desktop, and server platforms. + +Linux can boot without ACPI with "acpi=off" command line parameter, but +with ACPI the kernel gains the capabilities to handle power management. +For Windows, ACPI is a must-have firmware feature since Windows Vista. +CONFIG_GENERATE_ACPI_TABLE is the config option to turn on ACPI support in +U-Boot. This requires Intel ACPI compiler to be installed on your host to +compile ACPI DSDT table written in ASL format to AML format. You can get +the compiler via "apt-get install iasl" if you are on Ubuntu or download +the source from [17] to compile one by yourself. + +Current ACPI support in U-Boot is not complete. More features will be added +in the future. The status as of today is: + + * Support generating RSDT, XSDT, FACS, FADT, MADT, MCFG tables. + * Support one static DSDT table only, compiled by Intel ACPI compiler. + * Support S0/S5, reboot and shutdown from OS. + * Support booting a pre-installed Ubuntu distribution via 'zboot' command. + * Support ACPI interrupts with SCI only. + +Features not supported so far (to make it a complete ACPI solution): + * S3 (Suspend to RAM), S4 (Suspend to Disk). + * Install and boot Ubuntu 14.04 (or above) from U-Boot with legacy interface. + * Install and boot Windows 8.1/10 from U-Boot with legacy interface. + +Features that are optional: + * ACPI global NVS support. We may need it to simplify ASL code logic if + utilizing NVS variables. Most likely we will need this sooner or later. + * Dynamic AML bytecodes insertion at run-time. We may need this to support + SSDT table generation and DSDT fix up. + * SMI support. Since U-Boot is a modern bootloader, we don't want to bring + those legacy stuff into U-Boot. ACPI spec allows a system that does not + support SMI (a legacy-free system). + +So far ACPI is enabled on BayTrail based boards. Testing was done by booting +a pre-installed Ubuntu 14.04 from a SATA drive. Most devices seem to work +correctly and the board can respond a reboot/shutdown command from Ubuntu.
TODO List --------- - Audio - Chrome OS verified boot -- SMI and ACPI support, to provide platform info and facilities to Linux
References ---------- @@ -982,3 +1022,5 @@ References [13] http://events.linuxfoundation.org/sites/events/files/slides/elce-2014.pdf [14] http://www.seabios.org/SeaBIOS [15] doc/device-tree-bindings/misc/intel,irq-router.txt +[16] http://www.acpi.info +[17] https://www.acpica.org/downloads