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arm64: Update booting requirements for GICv3 in GICv2 mode 

The current requirements do not describe the case where a GICv3
system gets booted with system register access disabled, and
expect the kernel to drive GICv3 in GICv2 mode.

Describe the expected settings for that particular case.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2015-09-30 12:05:17 +01:00
parent 76e52dd01c
commit 6d32ab2d8a
1 changed files with 10 additions and 1 deletions
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11
Documentation/arm64/booting.txt
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@ -173,13 +173,22 @@ Before jumping into the kernel, the following conditions must be met:
the kernel image will be entered must be initialised by software at a
higher exception level to prevent execution in an UNKNOWN state.
For systems with a GICv3 interrupt controller:
For systems with a GICv3 interrupt controller to be used in v3 mode:
- If EL3 is present:
ICC_SRE_EL3.Enable (bit 3) must be initialiased to 0b1.
ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b1.
- If the kernel is entered at EL1:
ICC.SRE_EL2.Enable (bit 3) must be initialised to 0b1
ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b1.
- The DT or ACPI tables must describe a GICv3 interrupt controller.
For systems with a GICv3 interrupt controller to be used in
compatibility (v2) mode:
- If EL3 is present:
ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b0.
- If the kernel is entered at EL1:
ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b0.
- The DT or ACPI tables must describe a GICv2 interrupt controller.
The requirements described above for CPU mode, caches, MMUs, architected
timers, coherency and system registers apply to all CPUs. All CPUs must