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Hey, I'm new here, so if I seem like a n00b, it's probably because I am. Hopefully my question won't be too annoying.
I'm trying to use the NXTGCC 0.0.9 package as a starting point for custom firmware. The main point of my custom firmware is to swap out the virtual machine for a custom one. I can compile the NXTGCC firmware fine, and it loads with SAM-BA and works.
My modifications to the firmware so far are disabling a few parts of the NXT-G virtual machine (by commenting out some parts of c_cmd.c), and inserting a new file containing the implementation of the new virtual machine. I inserted into c_cmd.c some code which (hopefully) is supposed to translate calls to the NXT-G VM into calls to the new VM. It now compiles fine, however, when I load the firmware with SAM-BA and type "go 0x100000", the NXT crashes with a blank screen, and I have to put it back in SAM-BA mode and load a working firmware to make it function again.
Very little of my changed code executes on boot, all of which I am relatively confident is not likely to cause a crash. Is the VM normally called during boot? I don't believe so, but if someone can contradict me, that would be helpful information.
My hypothesis (which is likely wrong, but it's the only one I have -- help would be appreciated here) is that maybe parts of the firmware are being overwritten by the file system or something, since the new firmware is around 10KB larger than the NXTGCC firmware.
The address table thingy (not sure what it's called -- again, I'm a n00b) outputted when I make the new firmware is as follows:
Size after:
m_sched.elf :
section size addr
.text 126572 1048576
.text2 23072 1279744
.data 6180 2097152
.bss 46604 2103332
.comment 2970 0
.debug_aranges 592 0
.debug_pubnames 95 0
.debug_info 4366 0
.debug_abbrev 1012 0
.debug_line 3349 0
.debug_frame 276 0
.debug_str 353 0
.debug_loc 3214 0
.debug_ranges 456 0
Total 219111
Not sure if this helps in diagnosing the problem or not; if there's any more detail I need to provide for people to get an idea of what could be wrong, just ask.
Any help would be greatly appreciated.
Thanks in advance.
-Jeremy Rand
PS: I attempted to post this message two days ago, but I believe it got eaten by my client. If anyone receives a duplicate, I apologize.
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Message has 2 Replies:
 | | RE: Custom firmware crashing on boot
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| Here's two things to try since you've only swapped out the VM hich I assume is a replacement for the "c_cmd.c" file. 1. First there is a "#define" that specifies the start address of the file system. If you're 10K larger you're going to need to (...) (17 years ago, 27-Jun-07, to lugnet.robotics.nxt.nxthacking)
| | | Re: Custom firmware crashing on boot
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| (...) It is nice with some action. (...) OK, that is very good. (...) A quick question: Are you running binsert after you compile? It may be worthwhile to look at lines 50-55 in "Makefile". With some effort and a hex file editor you can check if (...) (17 years ago, 28-Jun-07, to lugnet.robotics.nxt.nxthacking)
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