hello Heinrich,
On Sat, 5 Dec 2020 at 15:01, Heinrich Schuchardt 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
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
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) {