Commit 87db537d authored by Aaro Koskinen's avatar Aaro Koskinen Committed by Ralf Baechle
Browse files

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: default avatarAaro Koskinen <aaro.koskinen@nokia.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11114/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent d00d9203

arch/mips/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -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

arch/mips/kernel/setup.c

+4 −0
Original line number Diff line number Diff line
@@ -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);

arch/mips/kernel/vmlinux.lds.S

+5 −0
Original line number Diff line number Diff line
@@ -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

CRA Git | Maintained and supported by SUSTech CRA and CCSE