Does the DryOS-shell allows access to the internal file systems ? - DryOS Development - CHDK Forum

Does the DryOS-shell allows access to the internal file systems ?

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Hello,

I want to access kernel, config and data files of my DryOS (PIXMA) system, and copy it to USB/Card or via WLAN/USB-OTG.

Therefore I had a deeper look into the visible command set of the DryOS shell, but did not found any file or mount commands (my shell access : https://chdk.fandom.com/wiki/DryOS_PIXMA_Printer_Shell). Also I wonder if there is another console next to this DryOS-shell as this seems not the native command shell to me. There is very little DryOS information around, so any tip how this OS deals with its file system would be very interesting to get forward. Thanks a lot, TiWe.


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Offline reyalp

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Re: Does the DryOS-shell allows access to the internal file systems ?
« Reply #1 on: 18 / August / 2019, 20:49:45 »
Nice work on that :)

The Dry shell on powershots does not include filesystem access. EvShell and Canon basic do. I don't know if either exist on the printer, and I don't think either is directly accessible from dryshell on the cameras.

The task and extask commands should give you a list of running tasks.

xd and xm should allow you to execute arbitrary code, with enough work.

If you can find a firmware update for your printer, reverse engineering that might provide some useful clues. You could also likely dump your firmware slowly using xd and some scripting.

A previous printer hack was https://chdk.setepontos.com/index.php?topic=11902.0 although I'm not sure significant details were ever published.
Don't forget what the H stands for.

Re: Does the DryOS-shell allows access to the internal file systems ?
« Reply #2 on: 08 / September / 2019, 16:33:42 »
Thanks for the hints. I attach a list of all 105 DryOS commands with some explanation I gatherd. It seems to me that this shell is limited to manufacturing diagnostic. I am going forward to access the system's NOR flash and some analytics, maybe I find options to emulate system or to activate a real OS command line shell. The printer hack you mentioned I had read before also and it has in deed very little DryOS info. BR, TiWe.

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Offline reyalp

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Re: Does the DryOS-shell allows access to the internal file systems ?
« Reply #3 on: 08 / September / 2019, 17:42:15 »
Thanks for the hints. I attach a list of all 105 DryOS commands with some explanation I gatherd. It seems to me that this shell is limited to manufacturing diagnostic.
Yeah dry shell is pretty limited on powershots.

FWIW, if you can script interaction with the serial console, it seems like it shouldn't be a huge amount of effort to dump RAM/ROM that way. If you get a dump of the firmware, finding a place you can use xm execute arbitrary code should be pretty straightforward.

edit:
Saw your talk comment on the wiki. That "welcome" message on your wiki talk from me is auto-generated, we really don't use talk for much. The forum is much better for discussion. I don't think the wiki lets you attach spreadsheet files. You could link your post with the attachment from a wiki page, or host it elsewhere like a google doc.
« Last Edit: 08 / September / 2019, 23:35:36 by reyalp »
Don't forget what the H stands for.


Re: Does the DryOS-shell allows access to the internal file systems ?
« Reply #4 on: 17 / January / 2020, 05:04:20 »
During my unsuccessful search for a way to reset the waste ink counter to revive a broken printer where the ServiceTool refused to do so by telling me that the function is not available on the printer (Error 002), I wrote some simple utilities to download and unpack Canon PIXMA printer firmware. It seems that it's also using DryOS.
Maybe it's interesting for your research?
https://github.com/leecher1337/pixma

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Offline reyalp

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Don't forget what the H stands for.

Re: Does the DryOS-shell allows access to the internal file systems ?
« Reply #6 on: 12 / June / 2022, 02:54:28 »
Thanks for the hints. I attach a list of all 105 DryOS commands with some explanation I gatherd. It seems to me that this shell is limited to manufacturing diagnostic. I am going forward to access the system's NOR flash and some analytics, maybe I find options to emulate system or to activate a real OS command line shell. The printer hack you mentioned I had read before also and it has in deed very little DryOS info. BR, TiWe.

Hello! I saw your post on the wiki and in this forum about the DryOS. I am also looking a way to access my Pixma MX897 also. Because it has a B200 error somehow, but I could still operate the scanner function by bypassing the ink checking when turning in on by using the tricks shared in the internet. The most annoying part is that it might be received/sent fax before so it will, after certain time, go to check the ink or try to print out something and will generate the B200 error again at that point of time. Then I need to turn it off and on using the tricks again.
So I wonder if clearing the data inside could help because resetting the settings is of no use. It still run the printing function after certain time.
I also wonder/imagine if there is a custom rom although I have also read the custom rom hack with python tools and analysis and the possible to feed it with custom rom.
But still, although it is possible, if it brick then cannot access it anymore.
I saw your screenshot, how did you access the DryOS?
If you could access, does it mean if it brick, you could restore the rom also through your method?

I have seen there is custom rom for EOS Camera series but not for Pixma, maybe it is not too worthy for making one?
It is a bit of waste to change a printer while it still could scan. I just use it as a scanner now. And give only 0.2 -0.3 dollar to print outside per page if necessary is more realistic and practical.
Its roller and scanning feature is the best thing of this machine while I understand that ink is the only a tool to generate long-term money for the company so they don't bother of practical user situation.

But truly speaking, if they sell the source code or toolkit for tweaking the printer feature, I would consider to buy this rather than ink nowadays for everything is going to digital. Seldom to do any print-out now. Scanning is more important and printing is reversely becoming an added-value instead of a main feature. Gotta follow the trends in the world. Japanese company is too conservative when something making money used to be, they just keep it like making a games will make Generation 1, Generation 2, Generation 3...Generation X...Generation Forever rather than developing something new but of course games like Final Fantasy is of different culture, they improve it every time including the gaming system, the animation and so on.

Well hopefully if the printer is still operable, I still look for a way to make use of it.

 

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