Commit c0b4e101 authored by Jonas Gorski's avatar Jonas Gorski Committed by Ralf Baechle
Browse files

MIPS: Add support for vmlinuz.bin appended dtb 



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: default avatarJonas Gorski <jogo@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: John Crispin <blogic@openwrt.org>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: James Hartley <James.Hartley@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/9741/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 1da8f179

arch/mips/Kconfig

+18 −0
Original line number Diff line number Diff line
@@ -2702,6 +2702,24 @@ 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

arch/mips/boot/compressed/head.S

+16 −0
Original line number Diff line number Diff line
@@ -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

arch/mips/boot/compressed/ld.script

+5 −1
Original line number Diff line number Diff line
@@ -29,8 +29,12 @@ SECTIONS 
		*(.image)

		__image_end = .;

		CONSTRUCTORS

	}

		. = ALIGN(16);

	}

	__appended_dtb = .;

	/* leave space for appended DTB */

	. += 0x100000;



	_edata = .;

	/* End of data section */

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