Hi Masahiro,
2016-10-04 20:19 GMT-07:00 Masahiro Yamada yamada.masahiro@socionext.com:
Hi.
Recently I implemented ARM Trusted Firmware BL31 for my SoCs.
But, I am wondering how the boot-flow should be.
Here is my situation.
[1] When my company developed its first ARMv8 SoC, I had to bring up the system very quickly.
I was familiar with U-Boot and Linux to some extent, but not with ATF at that time. Also I was too pressed, so I decided to build up the system without ATF.
The boot-flow was like this:
BootROM -> U-Boot SPL -> U-Boot proper -> Linux
In this flow, the secure runtime firmware is missing, so I used Spin-Table for the enable-method.
[2] Now I finished porting ATF BL31. The low-level init code (basic SoC init + DRAM initialization) already exists in U-Boot SPL. So, I am currently re-using SPL, like follows:
BootROM -> U-Boot SPL -> ATF BL31 -> U-Boot proper (=BL33) -> Linux
As far as I know, SPL can not load multiple images such as BL31, BL32, BL33 (here BL32 is optional). So, I hacked my SPL to load multi images and jump to BL31.
this is not entirely truth. If you look at zynqmp you will find out that if you work with atf as kernel and full u-boot as dtb then u-boot SPL can load two images. This is what I use. It is a trick but I am not using any changes to get it work.
[3] I am guessing most vendors use vendor-specific firmware for low-level init because I see many of ARMv8 SoCs disabling CONFIG_SPL. Correct?
I do use SPL exactly how as used without ATF. It means low level init is done in SPL in EL3.
Boot ROM -> Vendor proprietary firmware -> ATF BL31 -> U-Boot or UEFI (=BL33) -> Linux
[4] Is it a good idea to implement everything in ATF like Juno/FVP?
BL1 -> BL2 -> BL31 -> U-Boot or UEFI (BL33) -> Linux
We are using only BL31 and nothing else.
Recently I saw Simon's binman patches. It provides a fancy way to pack multiple firmware components into a single image, but I did not see the systematic way to load every entry in the image. (under way?)
I was wondering if I should move my low-level init code from SPL to ATF BL2 or somewhere.
Comments are welcome.
I use bootrom -> SPL -> ATF -> full u-boot.
I want to use SPL because we have all device drivers in u-boot and in ATF we have only serial driver. If you want to use BL2 just for low level init stuff you can but it is the question if this brings you any value.
Anyway check zynqmp. It is not perfect solution but it is at least temporary solution for just this case. FIT image has an option to add more images with load address and I think this is a support we should support in SPL. (doc/uImage.FIT/multi-with-loadables.its) Also there will be probably need to mark images with EL level this targets.
Thanks, Michal
-- Best Regards Masahiro Yamada _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot