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ARM: 8786/1: Debug kernel copy by printing 

It may happen that when we relocate the kernel we corrupt other
sensible memory (e.g. the memory needed by U-Boot for dealing
with bootm command) while copying the kernel. If we overwrite
the content of the memory area used by U-Boot's command bootm
(described by U-Boot's parameters bootm_low and bootm_size),
the kernel won't be able to boot. Troubleshooting the problem
then is not straightforward.

This commit allows the user to easily print information on
where the kernel gets copied from/to in order to help with the
design of the system memory map (e.g. bootm_low and bootm_size)
at boot up.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Chris Paterson <Chris.Paterson2@renesas.com>
Acked-by: Biju Das <biju.das@bp.renesas.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
hifive-unleashed-5.1
Fabrizio Castro 2018-08-21 18:54:13 +01:00 committed by Russell King
parent 5b394b2ddf
commit f3c899927e
1 changed files with 43 additions and 0 deletions
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43
arch/arm/boot/compressed/head.S
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@ -114,6 +114,35 @@
#endif
.endm
/*
* Debug kernel copy by printing the memory addresses involved
*/
.macro dbgkc, begin, end, cbegin, cend
#ifdef DEBUG
kputc #'\n'
kputc #'C'
kputc #':'
kputc #'0'
kputc #'x'
kphex \begin, 8 /* Start of compressed kernel */
kputc #'-'
kputc #'0'
kputc #'x'
kphex \end, 8 /* End of compressed kernel */
kputc #'-'
kputc #'>'
kputc #'0'
kputc #'x'
kphex \cbegin, 8 /* Start of kernel copy */
kputc #'-'
kputc #'0'
kputc #'x'
kphex \cend, 8 /* End of kernel copy */
kputc #'\n'
kputc #'\r'
#endif
.endm
.section ".start", #alloc, #execinstr
/*
* sort out different calling conventions
@ -450,6 +479,20 @@ dtb_check_done:
add r6, r9, r5
add r9, r9, r10
#ifdef DEBUG
sub r10, r6, r5
sub r10, r9, r10
/*
* We are about to copy the kernel to a new memory area.
* The boundaries of the new memory area can be found in
* r10 and r9, whilst r5 and r6 contain the boundaries
* of the memory we are going to copy.
* Calling dbgkc will help with the printing of this
* information.
*/
dbgkc r5, r6, r10, r9
#endif
1: ldmdb r6!, {r0 - r3, r10 - r12, lr}
cmp r6, r5
stmdb r9!, {r0 - r3, r10 - r12, lr}