Re: How much protection does an add-on GSM modem give me vs. built into phone ? - baseband-devel

4 Oct 2012

Denis 'GNUtoo' Carikli писал 04.10.2012 14:26:
...
  On Thu, 4 Oct 2012 00:32:48 +0200
 Peter Stuge &lt;peter(a)stuge.se&gt; wrote:

  John Case wrote:
  the real trick I am interested is isolating (or
at least
 controlling) the interaction between the baseband processor and   the
  application processor.  Using a computer with a
USB dongle gives   me
  that control ... would I have that same level of
control if we had
 free software running on the baseband processor, or is there still
 additional bleeding possible simpy by virtue of being built into
 the computer ? 
 In a smartphone it's almost not possible to distinguish the
 "computer" from the "GSM modem" anymore, because of how the
 hardware is constructed, so yes.  In some yes, in some no... it depend on how the
smartphone was
 designed:

 On one end some smartphones (openmoko GTA02,golden delicious GTA04), 
 the
 baseband is isolated(tough on GTA04 it has access to a GPS with no
 antenna(so it can't work)) . And on the other end there are 
 smartphones
 with qualcomm System on a chip...where the modem and the CPU are in a
 single chip:
 The modem part has the audio DSP connected to it, the GPS.
 And the baseband uses shared RAM memory and shared NAND(if I remember
 well)...
 And I'm not sure but maybe the baseband is even needed for booting 
 the
 main CPU...

 There are also systems in between like the galaxy S/Neuxs S that uses
 shared memory but do not have other problems... 
In addition to the above, there are some phones where baseband is 
completely
submissive to the AP, namely Galaxy SII. Basically it's exactly the 
same
as the USB dongle situation, but the dongle is integrated on the 
phone's
PCB.

...

 Denis. 
-- 
   WBR, Peter Zotov.