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comparison doc/TIFFS @ 224:2900fe603f8a

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beginning of MPFFS->TIFFS naming convention change
author Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
date Sun, 12 Jan 2014 07:59:00 +0000
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children 1852900ce9ea
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223:0848c7f419fd 224:2900fe603f8a
1 All TI GSM firmwares known to this author (FreeCalypso developer Space Falcon)
2 implement some kind of flash file system, or FFS. Several different FFS code
3 implementations, and correspondingly several different on-flash data formats,
4 have been used throughout the history of TI's involvement in the wireless
5 terminal business. The FFS incarnation of primary interest to the FreeCalypso
6 project is the one invented by Mads Meisner-Jensen at TI in the early 2000s
7 (at least according to the comments in the sources available to us), and it is
8 relevant to us in the following ways:
9
10 * When targeting the GSM modem in Openmoko's GTA01/02 smartphones, we need to
11 work with the original FFS from the factory (call it MokoFFS), the same FFS
12 as used by the mokoN firmwares: this FFS contains the IMEI and the RF
13 calibration values from the factory, which we most certainly don't want to go
14 without.
15
16 * The Leonardo firmware semi-src which we are using as the reference for
17 building our own full source, multi-target GSM fw contains a turnkey-working
18 implementation of this very FFS, using the on-flash format in question and
19 providing run-time APIs expected by the rest of the GSM fw suite. Following
20 the principle of ``if it ain't broke, don't fix it'', we can use this FFS not
21 only on the gtamodem target, but also on other targets, including those where
22 we would be starting from a blank state and thus have the freedom to use
23 whatever FFS we like.
24
25 * The original proprietary fw on the Pirelli DP-L10 phone also happens to use
26 an FFS in the same format. Pirelli's FFS does *not* contain the IMEI or any
27 of the RF calibration values though, and trying to reuse it directly for our
28 own FC GSM fw seems to be more trouble than benefit - so we'll probably have
29 our fw start with a blank TIFFS instead - but there is still insight to be
30 gained from in-vitro examination of captured Pirelli FFS images.
31
32 Naming
33 ======
34
35 I have previously referred to the FFS format in question as Mokopir-FFS or
36 MPFFS, from "Moko" and "Pirelli". I was originally hesitant to call it TIFFS,
37 as lacking the source code, I had no way of knowing whether the FFS format and
38 implementation were of TI's own invention, or something that TI licensed as a
39 black box from one of their many proprietary software partners. (I was unable
40 to identify it as any well-known, industry-standard FFS format, but absence of
41 evidence is not evidence of absence.) But now that we have TI's original source
42 code which implements this FFS (first the MV100-0.1.rar source, then the full
43 Leonardo one), complete with comments and a HISTORY file, we know that our FFS
44 was invented and implemented by someone named Mads Meisner-Jensen at TI - I'm
45 guessing in the SSA group in Nice, France.
46
47 I am now making a naming transition from MPFFS to TIFFS: there is really no
48 link between this FFS format and the Openmoko+Pirelli duo, other than the
49 happenstance of me having first encountered this FFS on these two GSM device
50 brands, and the name TIFFS is more neutrally-descriptive.