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