ARM: Auto calculate ZRELADDR and provide option for exceptions
As long as the zImage is placed within the 128MB range from the start of
memory, ZRELADDR (Address where the decompressed kernel will be placed,
usually == PHYS_OFFSET + TEXT_OFFSET) can be determined at run-time by
masking PC with 0xf80000000.
Running through all the Makefile.boot, all those zreladdr-y
addresses == 0x[0-f][08]00_0000 + TEXT_OFFSET can be determined at
run-time.
Option CONFIG_AUTO_ZRELADDR and CONFIG_ZRELADDR are introduced,
CONFIG_ZRELADDR _must_ be explicitly specified if:
- ((zreladdr-y - TEXT_OFFSET) & ~0xf8000000) != 0, which means
masking PC with 0xf8000000 will result in an incorrect address.
Currently this is only a problem on u300.
- or the assumption of the zImage being loaded by the bootloader within
the first 128MB of RAM is incorrect
- or when ZBOOT_ROM is used, where the above assumption is usually wrong.
[ukleinek: changed mask from 0xf0000000 to 0xf8000000 for mx1 and shark
+ some review fixes from the mailing list]
Original-Idea-and-Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Eric Miao <eric.miao@canonical.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index d27faa1..abf4d65 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -170,9 +170,16 @@
.text
adr r0, LC0
- ARM( ldmia r0, {r1, r2, r3, r4, r5, r6, r11, ip, sp})
- THUMB( ldmia r0, {r1, r2, r3, r4, r5, r6, r11, ip} )
+ ARM( ldmia r0, {r1, r2, r3, r5, r6, r11, ip, sp})
+ THUMB( ldmia r0, {r1, r2, r3, r5, r6, r11, ip} )
THUMB( ldr sp, [r0, #32] )
+#ifdef CONFIG_AUTO_ZRELADDR
+ @ determine final kernel image address
+ and r4, pc, #0xf8000000
+ add r4, r4, #TEXT_OFFSET
+#else
+ ldr r4, =CONFIG_ZRELADDR
+#endif
subs r0, r0, r1 @ calculate the delta offset
@ if delta is zero, we are
@@ -310,7 +317,6 @@
LC0: .word LC0 @ r1
.word __bss_start @ r2
.word _end @ r3
- .word zreladdr @ r4
.word _start @ r5
.word _image_size @ r6
.word _got_start @ r11