On Mon, Mar 23, 2020 at 11:23 PM Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 3/24/20 5:16 AM, Atish Patra wrote:
The DT used by U-Boot may be different from the DT being passed to the OS if the DT is loaded from external media such as network or mmc. In that case, the reserved-memory node needs to be copied to the DT passed to the OS.
The bootefi command works in the following sequence:
- copy the passed fdt of if none is passed the internal fdt
- call image_setup_libfdt() for the copy
- create memory reservations in the UEFI memory map
Cf. fef907b2e440 ("efi_loader: create reservations after ft_board_setup") 7be64b885a36 ("cmd: bootefi: Parse reserved-memory node from DT")
image_setup_libfdt() executes among others:
- fdt_chosen()
- arch_fixup_fdt()
Please, explain why you need to copy memory reservations, if arch_fixup_fdt() is executed inside the bootefi command:
As per my understanding, there can be two different DTs in U-Boot. 1. Internal device tree or DT passed from previous stage (gd->fdt_blob). This device tree is being used to boot OS as well. 2. User can load the DT from MMC/network to any valid address and use that address in bootefi/booti command line to boot OS.
efi_install_fdt copies DT from the given user address (via cmdline) and copies to the efi memory.
There is no need to 2nd copy for case 1 as the DT already contains the reserved-memory node. In case 2, the DT loaded from external media may not have the reserved memory regions set by the firmware. That's why we need to copy the reserved-memory nodes. Now, arch_fixup_fdt() is the last place to edit the DT passed to OS. The copy operation has to be done in arch_fixup_fdt. For case 1, fdtdec_add_reserved_memory will simply return without modifying the DT.
What would be the source of memory reservation that you would otherwise miss in the final device tree? Do you expect that the Linux device tree would lack reservation that are generated on the fly before U-Boot?
Best regards
Heinrich
Signed-off-by: Atish Patra atish.patra@wdc.com Reviewed-by: Bin Meng bmeng.cn@gmail.com
arch/riscv/lib/bootm.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c index 87cadad5016d..8ff8db6bf533 100644 --- a/arch/riscv/lib/bootm.c +++ b/arch/riscv/lib/bootm.c @@ -28,8 +28,8 @@ __weak void board_quiesce_devices(void)
int arch_fixup_fdt(void *blob) { -#ifdef CONFIG_EFI_LOADER int err; +#ifdef CONFIG_EFI_LOADER u32 size; int chosen_offset;
@@ -50,6 +50,12 @@ int arch_fixup_fdt(void *blob) /* Overwrite the boot-hartid as U-Boot is the last stage BL */ fdt_setprop_u32(blob, chosen_offset, "boot-hartid", gd->arch.boot_hart); #endif
/* Copy the reserved-memory node to the DT used by OS */err = riscv_fdt_copy_resv_mem_node(gd->fdt_blob, blob);if (err < 0)return err;return 0;