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author | 2012-02-10 18:07:07 -0800 | |
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committer | 2012-09-19 08:32:51 +0100 | |
commit | 6a6d55c38c8b4ee77b50a33f03ea09e75b18bf82 (patch) | |
tree | 5aa95a02f40aabc081fef2d454baaa3009352163 | |
parent | ARM: zImage/virt: hyp mode entry support for the zImage loader (diff) | |
download | linux-6a6d55c38c8b4ee77b50a33f03ea09e75b18bf82.tar.gz linux-6a6d55c38c8b4ee77b50a33f03ea09e75b18bf82.tar.bz2 linux-6a6d55c38c8b4ee77b50a33f03ea09e75b18bf82.zip |
ARM: virt: Update documentation for hyp mode entry support
Document the possibility of the kernel being entered in HYP mode.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
-rw-r--r-- | Documentation/arm/Booting | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting index a341d87d276e..0c1f475fdf36 100644 --- a/Documentation/arm/Booting +++ b/Documentation/arm/Booting @@ -154,13 +154,33 @@ In either case, the following conditions must be met: - CPU mode All forms of interrupts must be disabled (IRQs and FIQs) - The CPU must be in SVC mode. (A special exception exists for Angel) + + For CPUs which do not include the ARM virtualization extensions, the + CPU must be in SVC mode. (A special exception exists for Angel) + + CPUs which include support for the virtualization extensions can be + entered in HYP mode in order to enable the kernel to make full use of + these extensions. This is the recommended boot method for such CPUs, + unless the virtualisations are already in use by a pre-installed + hypervisor. + + If the kernel is not entered in HYP mode for any reason, it must be + entered in SVC mode. - Caches, MMUs The MMU must be off. Instruction cache may be on or off. Data cache must be off. + If the kernel is entered in HYP mode, the above requirements apply to + the HYP mode configuration in addition to the ordinary PL1 (privileged + kernel modes) configuration. In addition, all traps into the + hypervisor must be disabled, and PL1 access must be granted for all + peripherals and CPU resources for which this is architecturally + possible. Except for entering in HYP mode, the system configuration + should be such that a kernel which does not include support for the + virtualization extensions can boot correctly without extra help. + - The boot loader is expected to call the kernel image by jumping directly to the first instruction of the kernel image. |