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annotate compal-flash-boot-for-fc/README @ 993:d92e4aadeeb3

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target-utils/c139explore: a cleaner way of setting the fixed UART base address
author Mychaela Falconia <falcon@ivan.Harhan.ORG>
date Wed, 30 Dec 2015 22:12:35 +0000
parents 8eb7cb176a70
children
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8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
diff changeset
1 Compal phones have malicious wiring in their PCBs to disable Calypso's internal
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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2 boot ROM (nIBOOT input tied high instead of low). Therefore, flash sector 0
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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3 must always contain working boot code that allows the possibility of new code
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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4 download over the headset jack UART, and jumps to the main firmware in the rest
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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5 of the flash if no such download is taking place. In the absence of such good
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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6 boot code in flash sector 0 the phone is bricked.
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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7
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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8 Compal's own firmwares for these phones do feature a bootloader just as
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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9 described, but it has one defect: they put the boundary between the boot code
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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10 and the main firmware at address 0x2000, but the flash erase unit boundary
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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11 does not come until 0x10000. Therefore, every time the main fw needs to be
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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12 reflashed, flash sector 0 has to be erased and reprogrammed, creating a
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
diff changeset
13 bricking vulnerability.
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
diff changeset
14
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
diff changeset
15 Because Compal's original flash layout does not allow us to reuse their
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
diff changeset
16 bootloader totally untouched while replacing the main fw, and we'll have to
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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17 reflash our own version of the boot code at least the first time we reflash a
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
diff changeset
18 given phone from its official fw to FreeCalypso, we can take the liberty of
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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19 using a slightly patched version of Compal's boot code - with Compal's official
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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20 firmwares the bootloader part differs slightly from one fw version to the next
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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21 anyway.
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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22
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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23 The version of Compal's flash boot code built in this directory is intended to
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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24 be used with FreeCalypso firmwares. It is based on one of Compal's versions
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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25 that has no malicious features (no check of flash word 0x2060 and no requirement
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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26 of "1003" signature in the serially downloaded images at the most inconvenient
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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27 location), and it has been patched to transfer control to the main fw at 0x10058
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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28 instead of 0x20F8, i.e., main fw images are to be flashed at 0x10000 without
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
diff changeset
29 touching flash sector 0. Interrupt and exception version redirections have also
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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30 been patched accordingly; the specific interface between the boot code and the
8eb7cb176a70 compal-flash-boot-for-fc/README added
Mychaela Falconia <falcon@ivan.Harhan.ORG>
parents:
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31 main fw now mimics that of TI's TCS211 reference fw.