On 26-02-06, Ahmad Fatoum wrote: > Hi, > > On 2/6/26 11:02 AM, Marco Felsch wrote: > >> On 2/4/26 9:01 PM, Marco Felsch wrote: > >>> Add support to store a FDT within the scratch area. The user needs to > >>> query the location and size via imx_scratch_get_fdt() which can be used > >>> afterwards to write the actual FDT into it. > >>> > >>> Signed-off-by: Marco Felsch <[email protected]> > > >>> +config SCRATCH_FDT_SIZE > >>> + hex > >>> + default 0x0 > >>> + prompt "Scratch FDT size" > >>> + help > >>> + The size of the scratch area used as destination to load and optional > >>> + decompress the barebox builtin DTB into it. Can be 0x0 if early FDT > >>> + support is not requied. > >>> + > >>> + If specified, SCRATCH_FDT_SIZE <= SCRATCH_SIZE must be ensured. > >>> + > >>> + This option should match the OP-TEE's CFG_DTB_MAX_SIZE configuration > >>> + if used by OP-TEE. > >> > >> AFAIU, this is a workaround because OP-TEE doesn't accept outside > >> information about how big the DTB buffer is, just its base address. > > > > This is correct for the bl_params case. In case of transfer-lists the > > size could be detected by OP-TEE OS. > > > >> In that case, this should go to security/Kconfig and be named something > >> like PBL_OPTEE_DTB_MAX_SIZE. There's no need to ask every user that > >> configures barebox about this. > > > > This would bind the FDT support to OP-TEE but the FDT could be used by > > other boot binaries as well.In the speak of ARM, it could be used by > > the TF-A. In the speak of RISC-V, it could be used by opensbi. Therefore > > I made it generic. > > > > I wanted to avoid multiple Kconfig options to configure the scatch space > > for: > > - OP-TEE FDT > > - OpenSBI FDT > > - TF-A FDT > > > > I'm currently unsure if dropping the OP-TEE note from the help message > > helps. But I have no hard feelings about PBL_OPTEE_DTB_MAX_SIZE either. > > How about: > > struct imx_scratch_space { > union { > u8 __b[CONFIG_SCRATCH_SIZE]; > struct { > u32 bootrom_log[128]; > u32 reserved[128]; > struct optee_header optee_hdr; > u8 fdt[] __aligned(8);
This would require, that the 'fdt' element is always the last element. We could add a comment, but it's rather fragile IMHO. > }; > }; > }; > static_assert(sizeof(struct imx_scratch_space) > - offsetof(struct imx_scratch_space, fdt) > <= PBL_OPTEE_DTB_MAX_SIZE); This would introduce a very strict dependency for CONFIG_SCRATCH_SIZE to the not always visible PBL_OPTEE_DTB_MAX_SIZE. As you said: > >> In that case, this should go to security/Kconfig and be named something > >> like PBL_OPTEE_DTB_MAX_SIZE. There's no need to ask every user that > >> configures barebox about this. Therefore I would like to use your name suggestion PBL_OPTEE_DTB_MAX_SIZE but keep it loose like RK does. > The benefits I see: > - Just one argument to tune (CONFIG_SCRATCH_SIZE) like we already use > for Rockchip Rockchip is using two Kconfig switch too (ARCH_ROCKCHIP_ATF_FDT_SIZE). > - We still have a dedicated option that can be kept in-sync with the > exact option value in OP-TEE to find problems at compile-time > - Only those who actually use OP-TEE will be asked about > PBL_OPTEE_DTB_MAX_SIZE Good points! > Would this work for you? Please see above. Regards, Marco > > Cheers, > Ahmad > > > > > > Regards, > > Marco > > > > > >> > >> > >> Cheers, > >> Ahmad > >> > >> -- > >> Pengutronix e.K. | | > >> Steuerwalder Str. 21 | http://www.pengutronix.de/ | > >> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > >> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | > >> > >> > > > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | > > -- #gernperDu #CallMeByMyFirstName Pengutronix e.K. | | Steuerwalder Str. 21 | https://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
