From 87db537da4cd1bfad388511a3647bbb497d2fb61 Mon Sep 17 00:00:00 2001 From: Aaro Koskinen Date: Fri, 11 Sep 2015 17:46:14 +0300 Subject: [PATCH] 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 Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11114/ Signed-off-by: Ralf Baechle --- arch/mips/Kconfig | 14 ++++++++++++++ arch/mips/kernel/setup.c | 4 ++++ arch/mips/kernel/vmlinux.lds.S | 5 +++++ 3 files changed, 23 insertions(+) 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=.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 #include +#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