[PATCH] riscv: add BUILTIN_DTB support for MMU-enabled targets
Anup Patel
anup at brainfault.org
Mon Dec 28 06:59:41 EST 2020
On Sat, Dec 26, 2020 at 10:03 PM Vitaly Wool <vitaly.wool at konsulko.com> wrote:
>
> Sometimes, especially in a production system we may not want to
> use a "smart bootloader" like u-boot to load kernel, ramdisk and
> device tree from a filesystem on eMMC, but rather load the kernel
> from a NAND partition and just run it as soon as we can, and in
> this case it is convenient to have device tree compiled into the
> kernel binary. Since this case is not limited to MMU-less systems,
> let's support it for these which have MMU enabled too.
>
> Signed-off-by: Vitaly Wool <vitaly.wool at konsulko.com>
> ---
> arch/riscv/Kconfig | 1 -
> arch/riscv/mm/init.c | 12 ++++++++++--
> 2 files changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 2b41f6d8e458..9464b4e3a71a 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -419,7 +419,6 @@ endmenu
>
> config BUILTIN_DTB
> def_bool n
> - depends on RISCV_M_MODE
> depends on OF
>
> menu "Power management options"
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 87c305c566ac..5d1c7a3ec01c 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -194,12 +194,20 @@ void __init setup_bootmem(void)
> setup_initrd();
> #endif /* CONFIG_BLK_DEV_INITRD */
>
> + /*
> + * If DTB is built in, no need to reserve its memblock.
> + * OTOH, initial_boot_params has to be set to properly copy DTB
> + * before unflattening later on.
> + */
> + if (IS_ENABLED(CONFIG_BUILTIN_DTB))
> + initial_boot_params = __va(dtb_early_pa);
Don't assign initial_boot_params directly here because the
early_init_dt_scan() will do it.
The setup_vm() is supposed to setup dtb_early_va and dtb_early_pa
for MMU-enabled case so please add a "#ifdef" over there for the
built-in DTB case.
> + else
> + memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
> +
> /*
> * Avoid using early_init_fdt_reserve_self() since __pa() does
> * not work for DTB pointers that are fixmap addresses
> */
This comment needs to be updated and moved along the memblock_reserve()
statement.
> - memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
> -
> early_init_fdt_scan_reserved_mem();
> dma_contiguous_reserve(dma32_phys_limit);
> memblock_allow_resize();
> --
> 2.29.2
>
This patch should be based upon Damiens builtin DTB patch.
Refer, https://www.spinics.net/lists/linux-gpio/msg56616.html
Regards,
Anup
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