From c218bca74eeafa2f8528b6bbb34d112075fcf40a Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Wed, 26 Mar 2014 18:25:55 +0000 Subject: arm64: Relax the kernel cache requirements for boot With system caches for the host OS or architected caches for guest OS we cannot easily guarantee that there are no dirty or stale cache lines for the areas of memory written by the kernel during boot with the MMU off (therefore non-cacheable accesses). This patch adds the necessary cache maintenance during boot and relaxes the booting requirements. Signed-off-by: Catalin Marinas --- Documentation/arm64/booting.txt | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'Documentation/arm64') diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index a9691cc48fe3..beb754e87c65 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -111,8 +111,14 @@ Before jumping into the kernel, the following conditions must be met: - Caches, MMUs The MMU must be off. Instruction cache may be on or off. - Data cache must be off and invalidated. - External caches (if present) must be configured and disabled. + The address range corresponding to the loaded kernel image must be + cleaned to the PoC. In the presence of a system cache or other + coherent masters with caches enabled, this will typically require + cache maintenance by VA rather than set/way operations. + System caches which respect the architected cache maintenance by VA + operations must be configured and may be enabled. + System caches which do not respect architected cache maintenance by VA + operations (not recommended) must be configured and disabled. - Architected timers CNTFRQ must be programmed with the timer frequency and CNTVOFF must -- cgit v1.2.3-59-g8ed1b