Add support for detecting a vmlinuz.bin appended dtb and overriding the boot arguments to match the UHI interface. To ensure _edata / __apendend_dtb points to the actual end of the binary, align the data section to 16 bytes instead of the address cursor. Due to ld.script not going through the preprocessor, we can't check for MIPS_ZBOOT_APPENDED_DTB being enabled, so always reserve space for it. It should have no consequences for booting without it enabled except 1 MiB more ram usage during the uncompressing stage. Signed-off-by: Jonas Gorski <jogo@xxxxxxxxxxx> --- arch/mips/Kconfig | 18 ++++++++++++++++++ arch/mips/boot/compressed/head.S | 16 ++++++++++++++++ arch/mips/boot/compressed/ld.script | 6 +++++- 3 files changed, 39 insertions(+), 1 deletion(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 0986619..8aef377 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -2697,6 +2697,24 @@ choice look like a DTB header after a reboot if no actual DTB is appended to vmlinux.bin. Do not leave this option active in a production kernel if you don't intend to always append a DTB. + + config MIPS_ZBOOT_APPENDED_DTB + bool "vmlinuz.bin" + depends on SYS_SUPPORTS_ZBOOT + help + With this option, the boot code will look for a device tree binary + DTB) appended to raw vmlinuz.bin (with decompressor). + (e.g. cat vmlinuz.bin <filename>.dtb > vmlinuz_w_dtb). + + This is meant as a backward compatibility convenience for those + systems with a bootloader that can't be upgraded to accommodate + the documented boot protocol using a device tree. + + Beware that there is very little in terms of protection against + this option being confused by leftover garbage in memory that might + look like a DTB header after a reboot if no actual DTB is appended + to vmlinuz.bin. Do not leave this option active in a production kernel + if you don't intend to always append a DTB. endchoice endmenu diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S index 409cb48..c580e85 100644 --- a/arch/mips/boot/compressed/head.S +++ b/arch/mips/boot/compressed/head.S @@ -25,6 +25,22 @@ start: move s2, a2 move s3, a3 +#ifdef CONFIG_MIPS_ZBOOT_APPENDED_DTB + PTR_LA t0, __appended_dtb +#ifdef CONFIG_CPU_BIG_ENDIAN + li t1, 0xd00dfeed +#else + li t1, 0xedfe0dd0 +#endif + lw t2, (t0) + bne t1, t2, not_found + nop + + move s1, t0 + PTR_LI s0, -2 +not_found: +#endif + /* Clear BSS */ PTR_LA a0, _edata PTR_LA a2, _end diff --git a/arch/mips/boot/compressed/ld.script b/arch/mips/boot/compressed/ld.script index 5a33409..2ed08fb 100644 --- a/arch/mips/boot/compressed/ld.script +++ b/arch/mips/boot/compressed/ld.script @@ -29,8 +29,12 @@ SECTIONS *(.image) __image_end = .; CONSTRUCTORS + . = ALIGN(16); } - . = ALIGN(16); + __appended_dtb = .; + /* leave space for appended DTB */ + . += 0x100000; + _edata = .; /* End of data section */ -- 1.7.10.4
