On Thu, Jan 08, 2026 at 05:41:42PM +0100, Casey Connolly wrote: > > > On 29/12/2025 12:43, Sumit Garg wrote: > > From: Sumit Garg <[email protected]> > > > > Recently upstream TF-A/OP-TEE has started gaining support for Qcom > > platforms. RB3Gen2 being the first one and more to come. U-Boot in > > corresponding boot flow is packaged as a position independent executable. > > > > So, lets add a generic U-Boot defconfig for Qcom platforms to support > > TF-A/OP-TEE based TrustZone stack. Build command: > > > > $ make qcom_tfa_optee_defconfig > > $ make -j`nproc` DEVICE_TREE=qcom/qcs6490-rb3gen2 > > This would be better suited as a config fragment rather than a new > defconfig imo.
That's fine with me to add it as a config fragment. > > But more importantly, enabling OPTEE support in U-Boot doesn't imply > that it will be used, just that it's supported. There are real use-cases of OP-TEE in U-Boot for Qcom platforms like secure EFI variables based on OP-TEE secure storage. Have a look here [1]. And sure there will be more such use-cases like fTPM, KASLR etc. can be supported based on OP-TEE. [1] lib/efi_loader/efi_variable_tee.c > > So I think the more appropriate patch here would be to just enable > OP-TEE in qcom_defconfig (assuming the binary size isn't significantly > affected). The OP-TEE driver in U-Boot itself is probed based on DT and it's not only specific to Qcom platforms but every other platform using OP-TEE. > > Considering the other patch is based on this assumption that if OP-TEE > support is enabled then the board must be using it, a different approach > is definitely needed. Yeah that's true even with TF-A boot flow, there is possibility to boot without OP-TEE as well. However, TF-A generally doesn't provide a generic option to detect whether OP-TEE is running or not. > > When I was looking into this last year I remember discussing this same > issue from the Linux side, there is a good argument to be made that > OP-TEE support in Linux shouldn't be based on the devicetree - > particularly in the Qualcomm case where whether or not OP-TEE is used is > a simple software change, nothing to do with hardware. Sadly it's true for every other silicon vendor too. But OP-TEE support based on DT has become an ABI unless migration for OP-TEE support based on FF-A comes into picture. > > So in general I'm not particularly keen on this approach, I think it > /might/ be acceptable for U-Boot to have some fixup code to add the > OP-TEE node if OP-TEE is in use with the idea of phasing that out in > favour of runtime detection in the OS itself. I'd also expect that fixup > code to go in the generic U-Boot DT fixup code that runs before we jump > to the OS (like the EFI DT fixup function). The EFI DT fixup code is already there based on U-Boot DT. Have a look here: boot/image-fdt.c:627: fdt_ret = optee_copy_fdt_nodes(blob); In general on Arm platforms there isn't any SMC bus to detect dynamically if there is support for OP-TEE or not. That's why platform bus was choosen for the U-Boot and Linux OP-TEE driver. It's similar to how we have the SCM DT node for Qcom platforms. FF-A bus tries to solve that problem to unify that approach for future platform but U-Boot hasn't yet gained support for FF-A based OP-TEE driver too. Anyhow, this is the sanest way I can come up with to enable OP-TEE support in a general way for all the Qcom platforms. This is aligned with how OP-TEE support is detected for other silicon vendors too. -Sumit > > Kind regards, > > > > > For more information refer here: > > https://trustedfirmware-a.readthedocs.io/en/latest/plat/qti/rb3gen2.html > > > > Signed-off-by: Sumit Garg <[email protected]> > > --- > > configs/qcom_tfa_optee_defconfig | 7 +++++++ > > 1 file changed, 7 insertions(+) > > create mode 100644 configs/qcom_tfa_optee_defconfig > > > > diff --git a/configs/qcom_tfa_optee_defconfig > > b/configs/qcom_tfa_optee_defconfig > > new file mode 100644 > > index 00000000000..c398521770f > > --- /dev/null > > +++ b/configs/qcom_tfa_optee_defconfig > > @@ -0,0 +1,7 @@ > > +# Configuration for building a generic U-Boot image > > +# with support for TF-A/OP-TEE based Arm TrustZone stack. > > + > > +#include "qcom_defconfig" > > + > > +CONFIG_TEE=y > > +CONFIG_OPTEE=y > > -- > // Casey (she/her) >
