[PATCH 03/18] arm64: boot protocol documentation update for GICv3

[marc.zyngier@arm.com (Marc Zyngier)]

Linux has some requirements that must be satisfied in order to boot
on a system built with a GICv3.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 Documentation/arm64/booting.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt
index a9691cc..4a02ebd 100644
--- a/Documentation/arm64/booting.txt
+++ b/Documentation/arm64/booting.txt
@@ -131,6 +131,13 @@ 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, it is expected that:
+  - ID_AA64PFR0_EL1.GIC (bits [27:24]) must have the value 0b0001
+  - If EL3 is present, it must program ICC_SRE_EL3.Enable (bit 3) to
+    0b1 and ICC_SRE_EL3.SRE (bit 0) to 0b1.
+  - If the kernel is entered at EL1, EL2 must set ICC_SRE_EL2.Enable
+    (bit 3) to 0b1 and ICC_SRE_EL2.SRE (bit 0) to 0b1.
+
 The requirements described above for CPU mode, caches, MMUs, architected
 timers, coherency and system registers apply to all CPUs.  All CPUs must
 enter the kernel in the same exception level.
-- 
1.8.3.4