Alexander Shishkin said the following on 01/13/2010 05:36 AM:
On Tue, Jan 12, 2010 at 04:08:23 -0600, Nishanth Menon wrote:
Alexander Shishkin had written, on 01/12/2010 03:46 PM, the following:
On Tue, Jan 12, 2010 at 01:04:04 -0800, Tony Lindgren wrote:
* Nishanth Menon <nm@xxxxxx> [100112 09:31]:
Alexander Shishkin had written, on 01/12/2010 11:30 AM, the following:
On Tue, Jan 12, 2010 at 11:13:13 -0600, Nishanth Menon wrote:
Alexander Shishkin had written, on 01/12/2010 11:04 AM, the following:
diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S
index 69521be..0a5ec86 100644
--- a/arch/arm/mach-omap2/sleep34xx.S
+++ b/arch/arm/mach-omap2/sleep34xx.S
[...]
/* Store current cpsr*/
mrs r2, cpsr
stmia r8!, {r2}
@@ -520,6 +616,7 @@ clean_caches:
cmp r9, #1 /* Check whether L2 inval is required or not*/
bne skip_l2_inval
clean_l2:
+#if 0
my aversion to #if 0 kicks in here :(.. do we have an alternative
like using the CONFIG_ENABLE_OFF_MODE_JTAG_ETM_DEBUG or something
else?
Fair enough. I could replace it with "#if !defined(...)" as the first
thing that comes to mind. This way it will only take disabling the
config option to catch any possible regressions in between. Does this
sound reasonable?
sounds ok to me.. unless folks have ideas coz of clean_l2 label..
more comments might be useful before a rev2 of the patch..
The best solution would be to be able to toggle this via sysfs or
debugfs by swapping the sram code for idle loop when JTAG support
is needed.
Well, if you say, compile the ETM driver in, this will be needed most of
the time.
I can think of reasons for an against a sysfs entry (as part of
discussion -warning lot of self contradictions below- but I think
might save a bit of back and froth ;)):
for sysfs entry:
a) save and restore will have additional latency when you save a
chunk such as EMU domain regs - this will not be needed in
production phones, disabling it might pop up surprises
counter: having a disabled defconfig allows relevant folks to
enable on a need basis
counter to counter: what do you do when a user reports
an issue in a release and you'd want to debug it with
ETM on his platform other than doing a rebuild?
Well, my intention is to have it enabled for most of the cases only having
it disabled for testing purposes.
with a sysfs you can go either way, with proper #ifdeferry, you can get
the best of all worlds I guess.. I know in one of the products, a
similar patch was not taken in due to introduction of additional
scratchpad space and latencies - so there are folks who would like this
and those who would like to see this not present in the binary they
flash to thier device.
b) mostly a debug support -> only for blokes using ETM/JTAG
interfaces - not everyone can afford these (no offense to openOCD
guys - but they are still a bit away from being able to debug kernel
yet on OMAP)..
Not really, you can still make use of ETM without any additional hardware
attached.
For the unitiated (like me) link from Alex's offline email[1].
Regards,
Nishanth Menon
[1]
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c5d6c7708c3e58015b2e4e13e6cea02c8567a94e
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