On 26.10.20 14:42, Daniel Schwierzeck wrote:
Am Freitag, den 16.10.2020, 15:08 +0200 schrieb Stefan Roese:
Octeon has a specific boot header, when booted via SPI NOR, NAND or MMC.
Here the only 2 instructions are allowed in the first few bytes of the
image. And these instructions need to be one branch and a nop. This
patch adds the necessary nop after the nop, to that the common MIPS
image is compatible with this Octeon header.
The tool to patch the Octeon boot header into the image will be send in
a follow-up patch.
Signed-off-by: Stefan Roese <s...@denx.de>
Cc: Aaron Williams <awilli...@marvell.com>
Cc: Chandrakala Chavva <ccha...@marvell.com>
Cc: Daniel Schwierzeck <daniel.schwierz...@gmail.com>
---
arch/mips/cpu/start.S | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
index d0c412236d..6de2470cc2 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -75,8 +75,13 @@
ENTRY(_start)
/* U-Boot entry point */
+ /*
+ * Octeon needs special handling here, as the binary might be
+ * patched to add a boot header for SPI, NAND or MMC booting. Only
+ * one branch plus nop is allowed here.
+ */
I'd prefer a shorter and more imperative comment within one multi-line
comment block, e.g.
/*
* U-Boot entry point.
* Do not add instructions to the branch delay slot! Some SoC's
* like Octeon might patch the final U-Boot binary at this location
* with additional boot headers.
*/
Even better. Will change in v2.
b reset
- mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing
+ nop
#if defined(CONFIG_MIPS_INSERT_BOOT_CONFIG)
/*
@@ -123,6 +128,7 @@ ENTRY(_start)
#endif
reset:
+ mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing
the extra indentation of one space is only required for instructions in
delay slots and needs to be removed.
Yes, thanks for catching.
Thanks,
Stefan
