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Windows Phone Permanently Modifies MicroSD Cards, Warns Samsung
dotancohen writes "Don't put your MicroSD cards into Windows Phones. According to Samsung, doing so is a 'permanent modification' to the card, and it can no longer be used in other devices."
But what appears to have fried our card is the fact that any card inserted into a Windows Phone 7 device "will no longer be readable or writable on any other devices such as computers, cameras, printers, and so on" according to documentation on Samsung's site -- including, amazingly, the ability to format the card.
Sounds like the card is being "permanently modified" (and not for the better) to me.
From Microsoft's KB2450831 support article:
If this is even possible there is something really wrong with the SD card in question
You have to dig further into the links in the article to find out what is really happening. Apparently the Windows Phone 7 devices are stressing the SD cards in a manner which is not in-spec for a normal SD card. This means that a SD card which is perfectly fine by the normal spec might be ruined by the way the Windows Phone 7 OS uses the card.
This means that you will need a SD card which is certified under more stringent requirements in order to not be destroyed by the Windows Phone 7 OS.
On top of that the OS also completely reformats the card so that it is a "permanent" part of the device. It probably sets up special space for swap space and other OS-specific data structures so that they can be accessed quickly and easily by the OS but this results in the card not having a normal disk layout that other devices can read using default software.
Sapere aude!
Nope.
Anandtech (http://www.anandtech.com/show/4015/htc-surround-review-pocket-boombox/8) say:
The other interesting thing is that cards initialized on WP7 are locked to a specific device, and moreover, stop being recognized on the desktop - perhaps permanently. I took the card out of the Surround and spent considerable time trying to make it format, first on Windows, then OSX, and finally linux by trying to write zeros and random data to the disk using dd. This failed, as I only managed to get 'medium not present' errors every step of the way - in fdisk, gparted, every trick I know for really nuking storage.
So, it actually does trash the card. There may be a way around that, but if there is so far some fairly smart people have failed to find it.
I've been studying SD cards for the last few months and I've managed to dig up some heretofore "secret" leaked documents about SD Digital Rights Management mechanism and I think I know how such a permanent modification could be performed.
One of the things that all SD cards support is the ability to designate a certain portion (which can include ALL) of the card's block storage as "secure". Once designated as secure, the blocks in question cannot be read, written to, or the area resized without performing an authentication step with the card. This authentication step is known as "AKE".
I'm willing to bet that the phone is using this "secure" facility and marking the entire card, or some significant portion thereof, as a secure storage area.
There is a yellow sticker completely covering the SD slot that says it will void your warranty if it is removed. I think that's' warning enough that it isn't a general purpose SD card slot. It also required an SD card that is certified as Windows Phone 7 complaint. Currently no such cards exist.
So if we follow your link and find out what is "really happening," we find out that some blokes plugged a card into a phone and that it seemed to kill the card.
Of course if you read the second link I posted you'd see that Microsoft itself spells it out a bit more clearly:
When the operating system integrates the SD card with your phone:
From this point on, the phone's operating system uses all of the available memory as a single storage space for storing applications and data. The phone will stop working properly if you remove the SD card, and the SD card cannot be read by another phone, device, or PC.
It's not just one data point from some casual observer. The manufacturer of the operating system states quite clearly that this is the expected behavior.
Sapere aude!
The SD Card can be locked to a specific device using a password.
example:
http://www.embeddedarm.com/software/arm-linux-sdcard-security.php
An SD card can be locked using a password, or it can be set to permanent write protected mode.
Also the manufacturer of an SD card may not include the secure features in their cards (which would probably mean it wouldn't work on these phones)
From the linked article: ...
Technologic Systems has developed a Linux application named "sdlock" which can be used to manipulate SD card hardware-enforced password locks and set the card's permanent write-protect feature. Using a password protected SD card is a great way to ensure software security and/or to make sure your TS-7000 SBC based product cannot be used in an unintended matter once deployed. This utility is only available for the TS-7300 and TS-7400 products, which are configured with the TS-SDBOOT firmware.
Some of the possibilities include:
Password protecting SD Cards
Set the SBC to boot only locked SD Cards
Set the SD Card readable only on a specific SBC
Checksum verification of bootable SD Cards
Make an SD Card permanently write-protected
How To Use It
Usage and command line help for this command:
$ sdlock –help
Usage: sdlock [OPTION]
Controls SD card lock and permanent write-protect features.
General options:
-p, --password=PASS Use PASS as password
-c, --clear Remove password lock
-s, --set Set password lock
-u, --unlock Unlock temporarily
-e, --erase Erase entire device (clears password)
-w, --wprot Enable permanent write protect
-h, --help This help
Well that's the issue, it's NOT supposed to be removable storage. Even if it didn't "break" teh card it still wouldn't be general purpose removable storage. The phone reformats the card along with the internal storage to create a single Volume, kind of like a RAID mirror. Taking out the card would make you lose all your data, on both the card and the internal storage. The only reason it uses an SD card is because it's convenient to build, and it allows the different providers to use whatever size storage they want. In this phone, the SD card it not a user serviceable part.