On 07.12.20 13:50, Heinrich Schuchardt wrote:
On 07.12.20 06:15, Sughosh Ganu wrote:
hello Heinrich,
On Sat, 5 Dec 2020 at 15:01, Heinrich Schuchardt <xypron.glpk@gmx.de mailto:xypron.glpk@gmx.de> wrote:
On 11/26/20 7:40 PM, Sughosh Ganu wrote: > The Qemu platform emulator generates a device tree blob and places it > at the start of the dram, which is then used by u-boot. Use this dtb > only if CONFIG_OF_BOARD is defined. This allows using a different > device tree, using the CONFIG_OF_SEPARATE option. This dtb is attached > to the u-boot binary as a u-boot-fdt.bin file Dear Sughosh, thank your for this series which will allow us to better demonstrate and test capsule updates. I am not sure if the approach that you take at device-trees here is the right one. On QEMU the device-tree is generated on the fly by the QEMU binary depending on which devices the user has specified. Your idea is to replace this device-tree completely to be able to add extra elements (the EFI signature list, see patch 2/14). Thus a device-tree might be loaded that does not match the user selected devices. An alternative approach would be to apply all additions to the device-tree as an FDT overlay (or fixup). This would allow the dynamic parts of the QEMU device-tree still to be passed through.I will take a look at storing the public key as part of the fdt overlay, with a runtime fixup. Although, I think the issue that you are pointing to would be specific to Qemu and not other platforms. But I do see the merit in having the public-key certificate stored as part of an overlay. If I hit any issues while implementing this, I will get back to you. Thanks.
-sughosh
OpenSBI can supply a device-tree to U-Boot. So this would be an equivalent case.
Best regards
Heinrich
<sng_>: "I am unable to think of a simple and elegant way to generate the overlay dtb, since this would require creation of a corresponding dts file, compiling it into a dtb and then using this on the platform."
Jean-Jacques' patch series introduced some of the necessary code:
[PATCH PATCH v6 00/13] Add support for applications of overlays in SPL https://lists.denx.de/pipermail/u-boot/2019-October/387653.html https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
CONFIG_OF_OVERLAY_LIST is used to specify the overlays to be compiled. You will have to remove the CONFIG_SPL_LOAD_FIT_APPLY_OVERLAY and CONFIG_SPL_LOAD_FIT dependency.
Best regards
Heinrich
Could you, please, assess the pros and cons of the two approaches with respect to: * usability for capsule updates * applicability for non-QEMU systems * integration of DTB overlays with FIT images for other use cases Best regards Heinrich > > Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org <mailto:sughosh.ganu@linaro.org>> > --- > board/emulation/qemu-arm/qemu-arm.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/board/emulation/qemu-arm/qemu-arm.c b/board/emulation/qemu-arm/qemu-arm.c > index f18f2ed7da..e146d1cc50 100644 > --- a/board/emulation/qemu-arm/qemu-arm.c > +++ b/board/emulation/qemu-arm/qemu-arm.c > @@ -89,11 +89,13 @@ int dram_init_banksize(void) > return 0; > } > > +#if defined(CONFIG_OF_BOARD) > void *board_fdt_blob_setup(void) > { > /* QEMU loads a generated DTB for us at the start of RAM. */ > return (void *)CONFIG_SYS_SDRAM_BASE; > } > +#endif > > void enable_caches(void) > { >