From edb02645fd3853c4622b890b2677a45a08d788b7 Mon Sep 17 00:00:00 2001
From: Mark Brown <>
Date: Mon, 12 Apr 2021 16:19:50 +0100
Subject: [PATCH v1 0/3] arm64: Boot requirements clarifications

This series makes explicit our booting requirements in a number of
areas, mainly the initialisation of optional floating point features.
While no issues have been encountered it seems better to be explict,
particularly given that new extensions frequently require setup from
higher exception levels to be functional so our list of explicit
requirement is tending to become more and more exhaustive creating some
expecation that requirements will be stated clearly.

Due to a collision with my recent FGT series this series is based on top
of arm64/for-next/fgt-boot-init.

Mark Brown (3):
  arm64: Relax booting requirements for configuration of traps
  arm64: Explicitly require that FPSIMD instructions do not trap
  arm64: Explicitly document boot requirements for SVE

 Documentation/arm64/booting.rst | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

base-commit: 230800cd315cd5e2093e603cf7ee150b7591ce1a
arm64: Explicitly document boot requirements for SVE

We do not currently document the requirements for configuration of the
SVE system registers when booting the kernel, let's do so for completeness.

We don't have a hard requirement that the vector lengths configured on
different CPUs on initial boot be consistent since we have logic to
constrain to the minimum supported value but we will reject any late CPUs
which can't support the current maximum and introducing the concept of
late CPUs seemed more complex than was useful so we require that all CPUs
use the same value.

Signed-off-by: Mark Brown <>
1 file changed