I Mounted A 2 Gig Sd Card!, Surprise, it's possible! :) Options

[DrWowe]

Thanks C-Guys!

I was poking around the driver for their WiFi card to investigate something. Then, I realized that they completely replace the sharp_sdmmc kernel module with their own SD/SDIO stack. So just for fun, I installed it and surprise, I can now read, write, and mount a Sandisk 2 GB SD card. So far, it's been working very reliably.

Now, the catches:

1) It works fine on my C760 (running Cacko 1.12). But, when I tried to install the modules on my 6000, I got kernel oopses. So, it may be very sensitive to the model/kernel that is running. This is not that surprising since C760 is one of the few models listed as supported on their website.

2) vfat filesystems are fine. I had some problems with ext2. I fixed it by reformatting my card with "mke2fs -b 1024 /dev/mmcda1". This driver doesn't seem to like block sizes > 1024.


Anyway, if you want to repeat my experiment, just download and install this ipk, and reboot the Zaurus:

http://c-guys.net/cgi-bin/download/passche...n_arm.ipk&key=1

[qx773]

I copied a couple of big files, a 419MB ATI SDK and a 398MB Beyond the Red Line BattleStar Galactica free game demo, onto the Sandisk Ultra II SD card. One thing that I accidentally learned by doing this is that Windows XP ignores the SD card's write protect tab. That pushed the SD card contents over 1GB in size. On the Zaurus SL-C760, I copied the files from the SD card to the CF card and am currently starting to compute their MD5SUMs. That will take a while. I would be more concerned about SD cards which are larger than 2GB in size in case the Sharp code uses signed 32 bit integer representations which would cause integer representations that are larger than 2,147,483,647 (2^31 - 1) to be interpreted as negative numbers.

I know that the Sharp voice recorder will falsely think that a mostly empty 4GB CF card is out of disk space, probably due to the use of signed 32 bit integer representations for checking the available space.

What technique did you use to disassemble and reassemble the object file? I might have to do that with the Sharp voice recorder to disable its disk space check.

The MD5SUMs of the corresponding files are identical. The computation finished as I was finishing this message.

[speculatrix]

One thing that I accidentally learned by doing this is that Windows XP ignores the SD card's write protect tab.

I suspect that's more likely to be the card reader not being able to detect the thing on the card, I suspect it does nothing on the card and relies on a sensor in the card reader.