On 23/04/2019 10:22, Jens Wiklander wrote:
Hi Robert,
On Thu, Apr 18, 2019 at 10:19 PM Robert P. J. Day rpjday@crashcourse.ca wrote:
going over the u-boot.cfg generated from zynq_zed_defconfig, and noticed the following:
#define CONFIG_OPTEE_TZDRAM_BASE 0x00000000 #define CONFIG_OPTEE_TZDRAM_SIZE 0x0000000
i thought that was strange as CONFIG_OPTEE was not selected, so i checked, and here's the relevant snippet from lib/optee/Kconfig:
config OPTEE bool "Support OPTEE images" help U-Boot can be configured to boot OPTEE images. Selecting this option will enable shared OPTEE library code and enable an OPTEE specific bootm command that will perform additional OPTEE specific checks before booting an OPTEE image created with mkimage.
config OPTEE_TZDRAM_SIZE hex "Amount of Trust-Zone RAM for the OPTEE image" default 0x0000000 help The size of pre-allocated Trust Zone DRAM to allocate for the OPTEE runtime.
config OPTEE_TZDRAM_BASE hex "Base address of Trust-Zone RAM for the OPTEE image" default 0x00000000 help The base address of pre-allocated Trust Zone DRAM for the OPTEE runtime.
those two Kbuild directives are (strangely?) not dependent on OPTEE, which is why they show up in u-boot.cfg. is this deliberate? i know nothing about TEE, but it seems odd that OPTEE-related settings don't depend on OPTEE.
am i misreading something?
It seems that the dependency was removed by Rui in c7b3a7ee5351 ("optee: adjust dependencies and default values for dram").
If OPTEE_TZDRAM_SIZE and OPTEE_TZDRAM_BASE are needed or not depends on the platform and should be selected in some way by the platform.
We can probably zap those two defines. Do we really need them to verify the image ? No. Could we live without them ? Yes. You could just as easily have an environment variable and ignore the size, which is in effect what we do with most other load addresses anyway.
I'll patch that out.
rday
p.s. the MAINTAINERS entry for TEE seems incomplete as well:
TEE M: Jens Wiklander jens.wiklander@linaro.org S: Maintained F: drivers/tee/ F: include/tee.h F: include/tee/
one suspects that should include, at the very least:
- lib/optee
- include/config/optee
I understand that this is confusing. OP-TEE is supported by U-Boot in two in two ways which are orthogonal.
We have loading and booting OP-TEE which is handled by lib/optee. In this case U-Boot is used as a Secure world boot loader. This was added by Bryan.
Then there's the TEE subsystem which includes a driver for communicating with OP-TEE in Secure world. This is mostly to support the Android Verified Boot 2.0 (AVB) use case, but can be used for other purposes too. In this case U-Boot is a Normal world boot loader. This was added by me.
I happen to know something about how OP-TEE is loaded, but I don't know much about the boards on which U-Boot is used for that purpose. I guess the best would be if Bryan added an entry for lib/optee in MAINTAINERS.
and I'll patch that too :)
--- bod