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authorAaro Koskinen <aaro.koskinen@nokia.com>2015-09-11 17:46:14 +0300
committerRalf Baechle <ralf@linux-mips.org>2015-11-12 13:35:48 +0300
commit87db537da4cd1bfad388511a3647bbb497d2fb61 (patch)
tree68332abad3fa7ec4f239dbad95cd65756a685fe6 /arch
parentd00d920338382ceaefc643760daf9936ae9c5788 (diff)
downloadlinux-87db537da4cd1bfad388511a3647bbb497d2fb61.tar.xz
MIPS: vmlinux: create a section for appended DTB
For bootloaders that support booting only ELF kernels and load only ELF segments to memory there is no easy way to supply DTB without kernel recompilation. For that purpose, create a section called .appended_dtb that can be later updated with board-specific DTB using binutils e.g. at kernel installation time. Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11114/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/mips/Kconfig14
-rw-r--r--arch/mips/kernel/setup.c4
-rw-r--r--arch/mips/kernel/vmlinux.lds.S5
3 files changed, 23 insertions, 0 deletions
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 218aa67a2c52..71683a853372 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2736,6 +2736,20 @@ choice
help
Do not enable appended dtb support.
+ config MIPS_ELF_APPENDED_DTB
+ bool "vmlinux"
+ help
+ With this option, the boot code will look for a device tree binary
+ DTB) included in the vmlinux ELF section .appended_dtb. By default
+ it is empty and the DTB can be appended using binutils command
+ objcopy:
+
+ objcopy --update-section .appended_dtb=<filename>.dtb vmlinux
+
+ This is meant as a backward compatiblity convenience for those
+ systems with a bootloader that can't be upgraded to accommodate
+ the documented boot protocol using a device tree.
+
config MIPS_RAW_APPENDED_DTB
bool "vmlinux.bin"
help
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 6f142ee4a086..66aac55df349 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -39,6 +39,10 @@
#include <asm/smp-ops.h>
#include <asm/prom.h>
+#ifdef CONFIG_MIPS_ELF_APPENDED_DTB
+const char __section(.appended_dtb) __appended_dtb[0x100000];
+#endif /* CONFIG_MIPS_ELF_APPENDED_DTB */
+
struct cpuinfo_mips cpu_data[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(cpu_data);
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 07d32a4aea60..f4c23d9023be 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -132,6 +132,11 @@ SECTIONS
__appended_dtb = .;
/* leave space for appended DTB */
. += 0x100000;
+#elif defined(CONFIG_MIPS_ELF_APPENDED_DTB)
+ .appended_dtb : AT(ADDR(.appended_dtb) - LOAD_OFFSET) {
+ *(.appended_dtb)
+ KEEP(*(.appended_dtb))
+ }
#endif
/*
* Align to 64K in attempt to eliminate holes before the