mirror of
https://github.com/brain-hackers/u-boot-brain
synced 2024-07-22 19:09:43 +09:00
73c38934da
When the CPU is in non-secure (NS) mode (when running U-Boot under a
secure monitor), certain actions cannot be taken, since they would need
to write to secure-only registers. One example is configuring the ARM
architectural timer's CNTFRQ register.
We could support this in one of two ways:
1) Compile twice, once for secure mode (in which case anything goes) and
once for non-secure mode (in which case certain actions are disabled).
This complicates things, since everyone needs to keep track of
different U-Boot binaries for different situations.
2) Detect NS mode at run-time, and optionally skip any impossible actions.
This has the advantage of a single U-Boot binary working in all cases.
(2) is not possible on ARM in general, since there's no architectural way
to detect secure-vs-non-secure. However, there is a Tegra-specific way to
detect this.
This patches uses that feature to detect secure vs. NS mode on Tegra, and
uses that to:
* Skip the ARM arch timer initialization.
* Set/clear an environment variable so that boot scripts can take
different action depending on which mode the CPU is in. This might be
something like:
if CPU is secure:
load secure monitor code into RAM.
boot secure monitor.
secure monitor will restart (a new copy of) U-Boot in NS mode.
else:
execute normal boot process
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
|
||
|---|---|---|
| .. | ||
| cpu | ||
| dts | ||
| imx-common | ||
| include | ||
| lib | ||
| mach-at91 | ||
| mach-davinci | ||
| mach-highbank | ||
| mach-keystone | ||
| mach-kirkwood | ||
| mach-nomadik | ||
| mach-orion5x | ||
| mach-tegra | ||
| mach-versatile | ||
| mvebu-common | ||
| config.mk | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||