FreeCalypso > hg > freecalypso-sw
annotate gsm-fw/lldbg/README @ 978:1ee80bcb0fd0
fc-tmsh: omr (old-style memory read) command implemented
author | Mychaela Falconia <falcon@ivan.Harhan.ORG> |
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date | Thu, 10 Dec 2015 04:05:55 +0000 |
parents | f5affe83ba2d |
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lldbg hack (poor girl's substitute for JTAG) implemented
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1 The hack implemented in this directory is a poor girl's substitute for JTAG, |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
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2 concocted for the purpose of debugging hard crashes in the firmware. The |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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3 intended usage is that the developer seeking to troubleshoot perplexing |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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4 misbehavior in the firmware inserts a call to lldbg_entry() as a form of |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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5 breakpoint at the earliest place in the main fw where it is seen that something |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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6 has gone astray, and when the thread of code execution hits this lldbg_entry() |
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lldbg hack (poor girl's substitute for JTAG) implemented
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7 function, the regular Nucleus environment gets completely frozen. Lldbg entry |
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lldbg hack (poor girl's substitute for JTAG) implemented
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8 code saves all registers and the return address (LR) on whatever stack it is |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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9 was called on, then disables all interrupts and switches to its own stack which |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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10 is not used by any other part of the fw. |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
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11 |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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12 This lldbg code is linked together with the main fw when feature lldbg is |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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13 enabled in build.conf, but it stands as its own separate body. All functions |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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14 and variables within lldbg are prefixed with lldbg_ to avoid any clashes, and |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
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15 once this lldbg code gains control, it does everything on its own without making |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
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16 use of *any* part of the regular fw. The code that forms lldbg is based on |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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17 FreeCalypso target-utils (loadagent) and is fully independent of the regular fw. |
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lldbg hack (poor girl's substitute for JTAG) implemented
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18 |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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19 Lldbg uses its own UART input and output code as well: the entry code waits for |
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lldbg hack (poor girl's substitute for JTAG) implemented
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20 any previous output (presumably RVTMUX) to go out, then sends out an STX-wrapped |
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lldbg hack (poor girl's substitute for JTAG) implemented
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21 message to make the lldbg entry visible in rvtdump/rvinterf, preceded by 3 STX |
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lldbg hack (poor girl's substitute for JTAG) implemented
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22 characters to terminate any RVTMUX packet in progress. From this point onward |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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23 all further communication is done in an ASCII terminal fashion: upon seeing the |
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lldbg hack (poor girl's substitute for JTAG) implemented
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24 lldbg entry message, the user needs to kill rvtdump/rvinterf and switch to |
f5affe83ba2d
lldbg hack (poor girl's substitute for JTAG) implemented
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25 fc-serterm. All lldbg code runs with interrupts disabled, thus UART input and |
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lldbg hack (poor girl's substitute for JTAG) implemented
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26 output are polled. |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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27 |
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lldbg hack (poor girl's substitute for JTAG) implemented
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28 Once in lldbg mode, the user (developer) can execute various memory dump |
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lldbg hack (poor girl's substitute for JTAG) implemented
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29 commands to see the frozen state of the fw upon lldbg entry, and hopefully |
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lldbg hack (poor girl's substitute for JTAG) implemented
Space Falcon <falcon@ivan.Harhan.ORG>
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30 figure out what went wrong earlier. |