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-rw-r--r--target/linux/generic/pending-5.4/332-arc-add-OWRTDTB-section.patch84
1 files changed, 84 insertions, 0 deletions
diff --git a/target/linux/generic/pending-5.4/332-arc-add-OWRTDTB-section.patch b/target/linux/generic/pending-5.4/332-arc-add-OWRTDTB-section.patch
new file mode 100644
index 0000000000..ec89547726
--- /dev/null
+++ b/target/linux/generic/pending-5.4/332-arc-add-OWRTDTB-section.patch
@@ -0,0 +1,84 @@
+From 34ef04f3845ed2b47d57dd9d3b795b16e1f8185a Mon Sep 17 00:00:00 2001
+From: Evgeniy Didin <Evgeniy.Didin@synopsys.com>
+Date: Fri, 15 Mar 2019 18:53:38 +0300
+Subject: [PATCH] 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: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
+Signed-off-by: Evgeniy Didin <Evgeniy.Didin@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
+@@ -59,6 +59,16 @@
+ #endif
+ .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
+@@ -526,7 +526,7 @@ void __init handle_uboot_args(void)
+ ignore_uboot_args:
+
+ if (use_embedded_dtb) {
+- machine_desc = setup_machine_fdt(__dtb_start);
++ machine_desc = setup_machine_fdt(&__image_dtb);
+ if (!machine_desc)
+ panic("Embedded DT invalid\n");
+ }
+@@ -542,6 +542,8 @@ ignore_uboot_args:
+ }
+ }
+
++extern struct boot_param_header __image_dtb;
++
+ void __init setup_arch(char **cmdline_p)
+ {
+ handle_uboot_args();
+--- 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)