From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heinrich Schuchardt Date: Sat, 5 Dec 2020 10:31:35 +0100 Subject: [PATCH 01/14] qemu: arm: Use the generated DTB only when CONGIG_OF_BOARD is defined In-Reply-To: <20201126184110.30521-2-sughosh.ganu@linaro.org> References: <20201126184110.30521-1-sughosh.ganu@linaro.org> <20201126184110.30521-2-sughosh.ganu@linaro.org> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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. 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 > --- > 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) > { >