ResetSystem() was over-specified in the document. UEFI already documents
the behaviour of ResetSystem() sufficiently. Add notes on expected
behaviour when platform specific or standard interface methods are
available.

Resolves: #29
Signed-off-by: Grant Likely <grant.lik...@arm.com>
---
 source/chapter2-uefi.rst | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst
index 0cbddff..8a3ff1a 100644
--- a/source/chapter2-uefi.rst
+++ b/source/chapter2-uefi.rst
@@ -175,23 +175,16 @@ and the OS must use a device driver to control the RTC.
 UEFI Reset and Shutdown
 -----------------------
 
-The UEFI Runtime service ResetSystem() must implement the following commands,
-for purposes of power management and system control.
-
-- EfiResetCold()
-- EfiResetShutdown()
-  * EfiResetShutdown must not reboot the system.
-
-If firmware updates are supported through the Runtime Service of
-UpdateCapsule(), then ResetSystem() might need to support the following
-command:
-
-- EfiWarmReset()
-
-.. note:: On platforms implementing the Power State Coordination Interface
-   specification [PSCI]_, it is still required that EBBR compliant
-   Operating Systems calls to reset the system will go via Runtime Services
-   and not directly to PSCI.
+ResetSystem() is required to be implemented in boot services, but it is
+optional for runtime services.
+During runtime services, the operating system should first attempt to
+use ResetSystem() to reset the system.
+If ResetSystem() returns EFI_UNSUPPORTED, then the OS may fall back to
+an architecture or platform specific mechanism.
+
+On AArch64 platforms implementing [PSCI]_,
+if ResetSystem() is not implemented then the Operating System should fall
+back to making a PSCI call to reset or shutdown the system.
 
 Runtime Variable Access
 -----------------------
-- 
2.13.0

_______________________________________________
boot-architecture mailing list
boot-architecture@lists.linaro.org
https://lists.linaro.org/mailman/listinfo/boot-architecture

Reply via email to