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- From: Alexey Brodkin <abrodkin@synopsys.com>
- Subject: openwrt: arc - add OWRTDTB section
- This change allows OpenWRT to patch resulting kernel binary with
- external .dtb.
- That allows us to re-use exactky the same vmlinux on different boards
- given its ARC core configurations match (at least cache line sizes etc).
- ""patch-dtb" searches for ASCII "OWRTDTB:" strign and copies external
- .dtb right after it, keeping the string in place.
- Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
- ---
- arch/arc/kernel/head.S | 10 ++++++++++
- arch/arc/kernel/setup.c | 4 +++-
- arch/arc/kernel/vmlinux.lds.S | 13 +++++++++++++
- 3 files changed, 26 insertions(+), 1 deletion(-)
- --- a/arch/arc/kernel/head.S
- +++ b/arch/arc/kernel/head.S
- @@ -49,6 +49,16 @@
- 1:
- .endm
-
- +; Here "patch-dtb" will embed external .dtb
- +; Note "patch-dtb" searches for ASCII "OWRTDTB:" string
- +; and pastes .dtb right after it, hense the string precedes
- +; __image_dtb symbol.
- + .section .owrt, "aw",@progbits
- + .ascii "OWRTDTB:"
- +ENTRY(__image_dtb)
- + .fill 0x4000
- +END(__image_dtb)
- +
- .section .init.text, "ax",@progbits
-
- ;----------------------------------------------------------------
- --- a/arch/arc/kernel/setup.c
- +++ b/arch/arc/kernel/setup.c
- @@ -421,6 +421,8 @@ static inline int is_kernel(unsigned lon
- return 0;
- }
-
- +extern struct boot_param_header __image_dtb;
- +
- void __init setup_arch(char **cmdline_p)
- {
- #ifdef CONFIG_ARC_UBOOT_SUPPORT
- @@ -434,7 +436,7 @@ void __init setup_arch(char **cmdline_p)
- #endif
- {
- /* No, so try the embedded one */
- - machine_desc = setup_machine_fdt(__dtb_start);
- + machine_desc = setup_machine_fdt(&__image_dtb);
- if (!machine_desc)
- panic("Embedded DT invalid\n");
-
- --- a/arch/arc/kernel/vmlinux.lds.S
- +++ b/arch/arc/kernel/vmlinux.lds.S
- @@ -30,6 +30,19 @@ SECTIONS
-
- . = CONFIG_LINUX_LINK_BASE;
-
- + /*
- + * In OpenWRT we want to patch built binary embedding .dtb of choice.
- + * This is implemented with "patch-dtb" utility which searches for
- + * "OWRTDTB:" string in first 16k of image and if it is found
- + * copies .dtb right after mentioned string.
- + *
- + * Note: "OWRTDTB:" won't be overwritten with .dtb, .dtb will follow it.
- + */
- + .owrt : {
- + *(.owrt)
- + . = ALIGN(PAGE_SIZE);
- + }
- +
- _int_vec_base_lds = .;
- .vector : {
- *(.vector)
|
