Hi,
On Thu, Jun 04, 2015 at 05:35:04PM +0800, Yang Yingliang wrote:
> This patch provides the ability to boot using a device tree that is appended
> to the raw binary Image (e.g. cat Image <filename>.dtb > Image_w_dtb).
>
> Both BE and LE conditions are tested.
>
> Got references from e2a6a3aa ("ARM: zImage: Allow the appending of a device
> tree binary").
Passing the DTB is really the responsibility of the bootloader.
ARM_APPENDED_DTB was a transitional hack to allow non-DT-aware
bootloaders to boot new kernels that require a DT for arch/arm.
For arm64 DT has been required from the start, as mandated in
Documentation/arm64/booting.txt -- there are no "legacy" bootloaders to
support.
Can you explain your rationale for this change?
Cheers
---Dave
>
> Signed-off-by: Yang Yingliang <[email protected]>
> ---
> arch/arm64/Kconfig | 11 +++++++++++
> arch/arm64/kernel/head.S | 12 ++++++++++++
> arch/arm64/kernel/vmlinux.lds.S | 17 +++++++++++++++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7796af4..d402448 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -660,6 +660,17 @@ endmenu
>
> menu "Boot options"
>
> +config ARM64_APPENDED_DTB
> + bool "Use appended device tree blob to Image"
> + depends on OF
> + help
> + With this option, the boot code will look for a device tree binary
> + (DTB) appended to Image
> + (e.g. cat Image <filename>.dtb > Image_w_dtb).
> +
> + With this option, the size of Image will be extended to be 2MB
> aligned.
> + The 2MB memory followed by Image is used for FDT blob.
> +
> config CMDLINE
> string "Default kernel command string"
> default ""
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 19f915e..ac00c8a 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -274,6 +274,18 @@ ENDPROC(preserve_boot_args)
> * The dtb must be 8-byte aligned and live in the first 512M of memory.
> */
> __vet_fdt:
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> + ldr x21, =_edata
> + add x21, x21, x28
> + ldr w0, [x21]
> +#ifndef __AARCH64EB__
> + ldr w1, =0xedfe0dd0 // FDT magic word
> +#else
> + ldr w1, =0xd00dfeed
> +#endif
> + cmp w0, w1
> + b.ne 1f // no FDT found
> +#endif
> tst x21, #0x7
> b.ne 1f
> cmp x21, x24
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index a2c2986..c71bac3 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -54,6 +54,18 @@ PECOFF_FILE_ALIGNMENT = 0x200;
> #define PECOFF_EDATA_PADDING
> #endif
>
> +/*
> + * Set FDT pointer 2MB aligned to ensure
> + * it don't cross a 2-megabyte boundary.
> + */
> +FDT_FILE_ALIGNMENT = (1 << 21);
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> +#define FDT_EDATA_PADDING \
> + .fdt_edata_padding : { BYTE(0); . = ALIGN(FDT_FILE_ALIGNMENT); }
> +#else
> +#define FDT_EDATA_PADDING
> +#endif
> +
> #ifdef CONFIG_DEBUG_ALIGN_RODATA
> #define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT);
> #define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
> @@ -149,8 +161,13 @@ SECTIONS
> _sdata = .;
> RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE)
> PECOFF_EDATA_PADDING
> + FDT_EDATA_PADDING /* 2MB aligned */
> _edata = .;
>
> +#ifdef CONFIG_ARM64_APPENDED_DTB
> + . += (1 << 21); /* maximum 2MB for FDT blob */
> +#endif
> +
> BSS_SECTION(0, 0, 0)
>
> . = ALIGN(PAGE_SIZE);
> --
> 1.8.0
>
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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