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Any developers interested in working on CHDK firmware for DSLRs ?

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Offline mx3

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #50 on: 08 / February / 2008, 06:24:33 »
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Quote from: naplam on 08 / February / 2008, 05:56:36
I just checked I can change anything in the first section and the firmware is accepted but maybe that's because of the patch i made. But unfortunately the first section you upload to the cam is not used to update the camera's firmware -i changed the strings as you suggested- so it seems we can't load any code in the camera without writing the firmware flash.
what string have you changed?
what about: 00828590,"Update Firmware?"

Quote from: naplam on 08 / February / 2008, 05:56:36
I'm still not sure about the patch I made yesterday... I think it's working because it has now accepted a file with modifications on the second section.
try to revert to original version to be sure
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Offline naplam

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #51 on: 08 / February / 2008, 06:28:57 »
Quote from: mx3 on 08 / February / 2008, 06:24:33
what string did you changed?
what about: 00828590,"Update Firmware?"
Yes I changed that one, which is the last one you see before actually starting the update, among others, and I saw the old strings :(

I'll try to revert to the old firmware later. Right now I'm going to test iso 3200, maybe it works (i'll just switch iso 3200 and 1600 for a quick test).
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Offline naplam

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #52 on: 08 / February / 2008, 06:59:44 »
Damn, i now know why I was getting inconsistent results in the tests. I'm using eos utility to upload the firmware. Well, apparently, if the CF card has a firmware in it already, it uses that one instead of copying the one you specify!! so you have to format the card each time to make sure... I'll repeat all the tests again and post the results.
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Offline mx3

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #53 on: 08 / February / 2008, 07:09:59 »
waiting for clean experiment :-)
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Offline naplam

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #54 on: 08 / February / 2008, 07:23:41 »
Ok these are my conclusions:
- The first section is included in the checksum, it won't allow changes in the strings of the 1st section.
- Same goes for the second section
- A "fixed" firmware with bytes tweaked to complain with the checksum is accepted, I just uploaded it with the patch supposed not to check the checksum
- My patch isn't working, checksum is still checked :(
- GREAT NEWS!!!  :D i switched "Update firmware?" with "Update fhrmwbre?" (word alignment, a+1=b, i-1=h to fix checksum) AND it was displayed on the screen, so we can execute code on the camera WITHOUT writing to the flash! - now we must find out how the checksum is calculated and where it's stored.
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Offline mx3

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #55 on: 08 / February / 2008, 07:47:52 »
good work.
intresting results.

it seems to me checksum is not stored in file (but 1-4 bytes inside file are used for checksum adjustment)
I don't see any suspicious (checksum) at begining of file and end of it.

you checked offset 4 (between patched bytes).
have you checked ( +1 / -1 ) thing with two bytes nearby?
can you check this for bytes with 8(16) offset between each other?


this would narrow checksum size
« Last Edit: 08 / February / 2008, 07:49:35 by mx3 »
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Offline naplam

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #56 on: 08 / February / 2008, 08:18:54 »
Quote from: mx3 on 08 / February / 2008, 07:47:52
have you checked ( +1 / -1 ) thing with two bytes nearby?
can you check this for bytes with 8(16) offset between each other?
1-byte distance -> works
2-byte distance -> works
4-byte distance -> works
8 -> works
It looks like it's adding byte by byte.
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Offline mx3

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #57 on: 08 / February / 2008, 08:21:05 »
good.
so I think there are no problems with starting porting :-)
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Offline naplam

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #58 on: 08 / February / 2008, 11:09:13 »
AHHH I finally did it! there's a checksum at the beginning of the file, as well as some other checksum or something somewhere. First I calculated the file checksum, then I saw the message was similar but different (after it failed), then I applied my new patch and it worked. I calculated the file checksum and my patch bypassed the "internal" checks, killer combination. So right now I can upload anything I want :)
« Last Edit: 08 / February / 2008, 11:10:55 by naplam »
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Offline mx3

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Re: Any developers interested in working on CHDK firmware for DSLRs ?
« Reply #59 on: 08 / February / 2008, 11:11:32 »
Quote from: naplam on 08 / February / 2008, 11:09:13
AHHH I finally did it!

So right now I can upload anything I want :)

be careful.
I would suggest you to use CHDK approach ( don't touch flash)
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