Current Bootchart / breaking SD boot

Mike (mwester) mwester at
Thu Jul 10 01:15:50 CEST 2008

Marcelo wrote:
> On Wed, Jul 9, 2008 at 2:47 PM, Mike (mwester) <mwester at> wrote:
>> And pulling the battery out too (no current user-space images of which
>> I am aware actually power down the GSM, so if you aren't pulling out
>> the battery, you're not in "airplane mode"!!)
>  Most consumer electronics in this category don't really power down,
>  even if you press the physical "power off" button.  A tiny bit of the
>  system is still running to do miscellaneous stuff.  ARM9 processors
>  like the one in the OpenMoko have a sleep mode that freezes the system
>  state, but it's otherwise "on".

I must step in and correct a possible misconception here -- you are
correct, but it is important to note that in the case of cell phones,
powering off DOES put the GSM into a "safe" mode, where the GSM is
either completely without power, or is in a state where it has the RF
section shut down.

My commentary is not about the small amount of power used by devices in
the "off" state, rather it is about the fact that the GSM on the GTA01
and GTA02 is left in a fully-operational, completely up-and-running
state, even when you have shut down the Linux kernel and the PCF606xx
PMU chip has otherwise shut down the power to all other components in
the phone.

The troubles this might make for the unaware user range from the trivial
and very probable draining of the battery when the phone is supposedly
off, to the improbable and not-so-trivial.

>  I have always wondered about the real reason behind asking people to
>  turn off phones during take off and landing.  Recently I heard that
>  it's actually only one of the cases that matters, I think it was
>  landing.  Once I forgot that I had dropped my phone in my backpack even
>  before leaving out for the airport and I realised this only when I
>  arrived at my final destination.  I wondered how often that kind of
>  thing happens to people all over the world.

I'm not interested in starting an argument over the validity of the
rules.  They are as they are, and we -- er, I guess I mean the
user-space application software developers since we've already had the
discussion about this being hardware or kernel -- we need to at least
ensure that the phone is capable of following those rules.  Whether you
do, or not, is up to you.

I'll also point out that this is not limited to airplanes, my travels
have taken me to places with large signs advising that one is entering a
"blast zone" and cell phones are to be turned off...  Again, if a user
chooses to comply or not is up to them, but at least they shouldn't be
left believing that they complied by powering off the phone when in fact
the GSM is merrily conversing with the nearest tower all by itself...

>  Marcelo

Mike (mwester)

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