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

Colin Cross ccross at android.com
Sun Feb 19 18:53:50 UTC 2012


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.


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