[Ce-android-mainline] ram console proposal update and questions

Shuah Khan shuahkhan at gmail.com
Sun Feb 19 20:12:34 UTC 2012


On Sun, Feb 19, 2012 at 11:53 AM, Colin Cross <ccross at android.com> wrote:
> On Sun, Feb 19, 2012 at 10:34 AM, Shuah Khan <shuahkhan at gmail.com> wrote:
>> I started testing android ram console driver on x86.
>>
>> The location I chose is drivers/char - please let me know if there is
>> a better suitable location.
>> I started out with error leg testing by leaving EARLY_SIZE as at its
>> default value of 0. As expected it failed.
>> However, I expected it to fail with an error message that indicates
>> that the EARLY_SIZE is invalid. I plan to
>> make necessary changes to indicate what is really wrong.
>>
>> [    0.000000] ram_console: buffer           (null), invalid size 0,
>> datasize 18446744073709551604
>>
>> What are some of the values used on Android devices for this config parameter?
>
> We tend not to use CONFIG_ANDROID_RAM_CONSOLE_EARLY_INIT at all.  For
> early crash problems, CONFIG_DEBUG_LL is easier to use.  In fact, in a
> big rewrite of ram_console for our android-3.3 tree (which should be
> published soon), I dropped early ramconsole support completely.
>
> For size, we use something between 128KB and 2MB.  128KB is plenty to
> get a few panics without losing context on what was happening before
> the panic, 2MB is enough to store a couple calls to sysrq-w or sysrq-t
> when debugging a deadlock.

Colin,

Do you mind sharing the latest source if it is ready so, I can start
using it as a base for integration into the mainline. Thanks for your
tips. I will stop testing EARLY_INIT. What about
RAM_CONSOLE_ERROR_CORRECTION code? Is that staying in the latest
re-write?

Thanks,
-- Shuah


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