Page 2 of 2

Posted: 27 Dec 2010, 11:24
by nicolas813
Hi Josh and thanks for your reply.

For the purpose of booting from switchable device, we should focus on the devices that provide read/write storage (SD).

If there are very few such devices, then it would be good to be able to list them and only provide the switch logic for them. Can you imagine adding a particular attribute into the usb_modeswitch database to state that a given device provides read/write storage or at least an SD (or micro-SD) slot ?

Also, it all those "r/w storage capable" devices share a common switching logic (sending a given string to a given endpoint), we can avoid porting others switching logic (SCSI eject, huawei mode, sierra mode, sony mode...). What manufacturer are the four devices you own, that provide r/w storage ?

Also, do you know of a possible way to access the read/write storage before switching the device ? Or at least, to detect whether an SD card is inserted into the slot or not, before switching ?

My goal is to avoid unnecessary switching if a switchable device is apparently not a bootable one.


Posted: 27 Dec 2010, 17:09
by Josh
AFAIK, when we are talking about read/write storage we can refer to the SD slot only. All recent devices expose the install storage as a (fake) CDROM that cannot be altered except when reflashing the firmware.

I have to check if there are devices or device "families" that make the SD slot visible before switching but there are certainly only a tiny few of them. Most don't.

My test devices are (intentionally) all from different makers, with different mode switch procedures. If you want to include the majority of devices with one single switch command, you can pick the ones with "eject" switching (see the config file "19d2:2000" which should work with almost everyone of them).

As for identifying mode-switching devices with SD capability, I don't know how to do that ...
I have no information which models would have no SD slot, so I can't add precise parameters to the configuration. But as I said, it's generally safe to assume they have got one.

How to check for inserted SD storage card before switching, I have no idea about that.

Posted: 27 Dec 2010, 18:37
by nicolas813
Yes, of course, when talking about r/w storage, I talk about the SD slot, not the fake CDROM, which is in practice mostly read-only.

My device is a 0af0:7501 (Option Icon 411, re-branded under several GSM operator names).

It apparently requires a different switching command than the common SCSI eject, and of course I want this one to be bootable through GRUB2.

I now understand that most recent devices include a SD slot. Right ?

Anyway, thanks for clarifying my understanding.


Stupid Question?

Posted: 17 Jun 2012, 14:04
by Tomsk
I've read through this thread with great interest - some excellent thoughts and testing going on here. I have a potentially stupid question:

Couldn't we just boot from the virtual cd, and then perform the modeswitch when booted, using the sd card for writable files? I'm sure I understood that the virtual cd could be left accessible once the modeswitch is performed using the .deb referred to earlier in the thread...

I'm new to this idea, but really want to get to a position where I can boot from the option 411 and then enable the modem - so apologies if I've missed something fundamental.

Did this ever get to a solution or a How To? Alternatively, might there be alternative hardware where this is possible?