On 10/31/2012 02:37 AM, Scott Wood wrote:
On 10/30/2012 04:26:16 AM, Prabhakar Kushwaha wrote:
On 10/30/2012 07:34 AM, Scott Wood wrote:
Previously, in many if not all configs we were creating overlapping
TLB entries
which is illegal. This caused a crash during boot when moving
p2020rdb NAND SPL
into L2 SRAM.
Signed-off-by: Scott Wood <scottw...@freescale.com>
Cc: Prabhakar Kushwaha <prabha...@freescale.com>
Cc: Andy Fleming <aflem...@freescale.com>
--
Prabhakar, please test that debug still works.
During RAMBOOT, both "temporary debug TLB entry" and "execution TLB
entry" is same. So moving "temporary debug TLB entry" creation after
"execution TLB entry resizing" will make sure of debugging during
NAND ramboot, SPI and SD boot.
But for NOR & NAND SPL there is a problem because boot-up TLB as
0xfffff000 and temporary debug TLB as 0xEFF80000. So we require to
create temporary TLB entry to support early debugging.
I will suggest to split the CONFIG_SYS_PPC_E500_DEBUG_TLB define into
2 parts.
1) For NOR , NAND spl debugging
2) For RAMBoot: After resizing of execution TLB
I'd rather not see this split this up. This file is too much of a
complicated ifdef mess already.
The window during which you won't be able to use breakpoints is not
that large.
There are other debugging techniques that can be used.
Can you please share the other techniques. It will help us in future.
Meanwhile, I wasted time debugging the problems that this extra TLB
entry caused -- and every time I try to reason about what's going on
in this file, I now have one more thing to consider (which is really
several more things due to all the different scenarios). Not exactly
the desired outcome of something meant to help debugging.
Debugger is present to help in these scenario for faster and effective
debugging.
My effort is to make as much as possible u-boot code to be debbug-able.
From now on, we have to take care of extra temporary debug TLB entry.
But this should not mean, no new TLB entries can be created depending
upon requirement. This TLB entry is required for debugging in AS1
execution space.
if everything is perfect, debugging is even not required. but if
something broken in AS1, debugger is best/shortest way to debug.
Also, we should not be creating this entry at any time during the SPL.
I believe it should not be required as NAND SPL never required. But
still need to check once this framework is pushed for mpx85xx platforms
I made following changes in the patch and tested across P1010RDB for
NOR, NAND-SPL, NAND Ramboot and SPI boot debugging.
Please note I used only this patch after replacing MINIMAL_SPL with
CONFIG_NAND_SPL.
diff --git a/arch/powerpc/cpu/mpc85xx/start.S
b/arch/powerpc/cpu/mpc85xx/start.S
index ac17f9d..c00db4a 100644
--- a/arch/powerpc/cpu/mpc85xx/start.S
+++ b/arch/powerpc/cpu/mpc85xx/start.S
@@ -282,7 +282,7 @@ l2_disabled:
isync
.endm
-#if defined(CONFIG_SYS_PPC_E500_DEBUG_TLB) && !defined(CONFIG_NAND_SPL)
+#if defined(CONFIG_SYS_PPC_E500_DEBUG_TLB) && !defined(MINIMAL_SPL)
/*
* TLB entry for debuggging in AS1
* Create temporary TLB entry in AS0 to handle debug exception
@@ -309,16 +309,6 @@ l2_disabled:
CONFIG_SYS_MONITOR_BASE, MAS2_I|MAS2_G, \
CONFIG_SYS_PBI_FLASH_WINDOW, MAS3_SX|MAS3_SW|MAS3_SR, \
0, r6
-#else
-/*
- * TLB entry is created for IVPR + IVOR15 to map on valid OP code
address
- * because "nexti" will resize TLB to 4K
- */
- create_tlb1_entry CONFIG_SYS_PPC_E500_DEBUG_TLB, \
- 0, BOOKE_PAGESZ_256K, \
- CONFIG_SYS_MONITOR_BASE, MAS2_I, \
- CONFIG_SYS_MONITOR_BASE, MAS3_SX|MAS3_SW|MAS3_SR, \
- 0, r6
#endif
#endif
@@ -520,6 +510,24 @@ nexti: mflr r1 /* R1 = our
PC */
msync
tlbwe
+#if defined(CONFIG_SYS_PPC_E500_DEBUG_TLB) && !defined(MINIMAL_SPL)\
+ && defined(CONFIG_SYS_RAMBOOT)
Get rid of that CONFIG_SYS_RAMBOOT. We don't set it anymore for SPL
as of this patchset. And the SPL payload is precisely when I saw
problems with this!
I paste this just for reference. It should be updated in v2 version of
this SPL patch series.
+/*
+ * TLB entry for debuggging in AS1
+ * Create temporary TLB entry in AS0 to handle debug exception
+ * As on debug exception MSR is cleared i.e. Address space is changed
+ * to 0. A TLB entry (in AS0) is required to handle debug exception
generated
+ * in AS1.
+ * TLB entry is created for IVPR + IVOR15 to map on valid OP code
address
+ * because "nexti" has resized execution TLB entry to 4K
+ */
+ create_tlb1_entry CONFIG_SYS_PPC_E500_DEBUG_TLB, \
+ 0, BOOKE_PAGESZ_256K, \
+ CONFIG_SYS_MONITOR_BASE & 0xfffc0000, MAS2_I, \
+ CONFIG_SYS_MONITOR_BASE & 0xfffc0000,
MAS3_SX|MAS3_SW|MAS3_SR, \
+ 0, r6
+#endif
+
/*
* Clear out any other TLB entries that may exist, to avoid conflicts.
* Our TLB entry is in r14.
You *cannot* put this entry into the TLB until we've cleared out the
unknown previous contents of the TLB.
OK. We can put it just after clearing TLB entries.
Regards,
Prabhakar
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