I am going to get an SD980 soon - page 2 - Firmware Dumping - CHDK Forum
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I am going to get an SD980 soon

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Offline RaduP

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Re: I am going to get an SD980 soon
« Reply #10 on: 09 / September / 2009, 02:47:47 »
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Ok, I guess the only way to know is to blink the LED if the signature is found. If the LED blinks, it means that the write function doesn't work as before, if it doesn't blink then the encryption is different, right?
And possibly have another LED blink right at the beginning of the code to make sure the code is loaded and executed.
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Offline reyalp

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Re: I am going to get an SD980 soon
« Reply #11 on: 09 / September / 2009, 04:26:03 »
Yup, that pretty much covers it.

Another possibility is finding something that matches your signature but isn't what you are looking for.
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Offline RaduP

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Re: I am going to get an SD980 soon
« Reply #12 on: 09 / September / 2009, 04:42:24 »
Yeah, I guess if Canon changed the magic structure where the pointer is (such as adding new functions before the write function) then the pointer will be found but won't be working.
I really wish the person who wrote the udumper would explain the magic behind finding that pointer :)
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Offline whoever

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Re: I am going to get an SD980 soon
« Reply #13 on: 09 / September / 2009, 10:28:10 »
Quote from: RaduP on 09 / September / 2009, 04:42:24
I really wish the person who wrote the udumper would explain the magic behind finding that pointer
What person? It was a collective effort by a group of magicians. You can follow it almost from conception here. Do read it -- you will learn it takes some voodoo magic (such as zeroing a part of RAM, however mundane it sounds). If you figure out how to make it work, it'll be great help to others. Awh well, of course it lacks the excitement of blinking it through a keyhole...

And what's more -- don't forget what "H" stands for, as somebody uses to say.
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Offline RaduP

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Re: I am going to get an SD980 soon
« Reply #14 on: 09 / September / 2009, 14:46:43 »
Oh, ok, makes much more sense now, thanks for posting it :)
It's also good to know that some of the wizards who wrote that code are still here :)
I am still confused about a few things though.
For example, why does it not work with the firmware update method?
And I was wandering if some wizard of the ARM assembly could maybe figure out how the write function works, so we can make our own (or at least copy and modify it to remove all the checks and stuff).
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Offline reyalp

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Re: I am going to get an SD980 soon
« Reply #15 on: 09 / September / 2009, 18:35:51 »
Quote from: RaduP on 09 / September / 2009, 14:46:43
And I was wandering if some wizard of the ARM assembly could maybe figure out how the write function works, so we can make our own (or at least copy and modify it to remove all the checks and stuff).
There's no wizardry involved, it's just a bunch of work. You can't just copy the function and run it on other cameras, because it relies on OS data structures that are at different addresses, and also eventually relies MMIO addresses that vary between hardware.
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Offline RaduP

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Re: I am going to get an SD980 soon
« Reply #16 on: 09 / September / 2009, 19:55:50 »
Oh, I know that, of course the IO addresses must be defined for each camera (or maybe camera family).
But from reading that thread it seems that the sd write function is designed so it won't have to rely much on the OS, which is the reason why it was chosen to do the job at hand.
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Offline reyalp

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Re: I am going to get an SD980 soon
« Reply #17 on: 09 / September / 2009, 20:47:10 »
Quote from: RaduP on 09 / September / 2009, 19:55:50
Oh, I know that, of course the IO addresses must be defined for each camera (or maybe camera family).
But from reading that thread it seems that the sd write function is designed so it won't have to rely much on the OS, which is the reason why it was chosen to do the job at hand.
No, it was chosen because it happens to work after some parts of the OS have been blown away by diskboot. Important difference.
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Offline RaduP

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Re: I am going to get an SD980 soon
« Reply #18 on: 09 / September / 2009, 21:06:49 »
Ok, now I am totally confused :)
From the first posts of this thread: http://chdk.setepontos.com/index.php/topic,221.0.html it seems that WriteSDCard() is part of a special section of the firmware that does not require the OS to run (it's sort of independent of the OS, and used for rescue purposes, maybe if the flashing went wrong or something).
So then it wouldn't make sense for it to require the OS to be running, right?

Am I missing something here?
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Offline reyalp

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Re: I am going to get an SD980 soon
« Reply #19 on: 09 / September / 2009, 22:01:01 »
Quote from: RaduP on 09 / September / 2009, 21:06:49
Am I missing something here?
Yes, several things. I suggest going back and reading the thread more carefully, because it directly contradicts pretty much everything you've said above.

edit:
reference to the actual code in a firmware dump would also correct those mistakes.
« Last Edit: 09 / September / 2009, 22:02:35 by reyalp »
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