[Galaxy Note GT-N7000 General] shoey63:
Have a read of of this guys. It will give you an insight into Entropy's thinking on "brickbug" issue. The key points to consider are "secure erase" ie. Dangerous CWM.zip or flashing ROM with format commands and unpatched update-binary. This is what Samsung have patched in new JB kernel.

"Non-secure erase". Samsungs patch causes "secure-erase " commands to default to this. It is also what happens when you wipe on stock ICS, or.... STOCK JB KERNEL!!!! I seriously doubt Entropy will ever declare this mode of wiping safe.

"Plain old format" This is what GB kernels and Philz and hydracore etc. use. Safest way to wipe on "brickbug" affected device. No -one has bricked emmc wiping this way.

Submitted for everyone's edification;)

Quoting Entropy 512 from here http://xdaforums.com/showthread.php?p=32131268 "There have been a few cases of claimed bricks from stock recovery. However Samsung is adamant that nonsecure erase is safe. We probably won't know until their new. kernel patch starts getting deployed to affected devices.

Go figure, first device to receive a kernel with the patch (simply due to update timing) didn't need it. (I9300).

An update-binary or recovery built with BOARD_SUPPRESS_EMMC_WIPE is safe - the strings test you ran confirms that is a safe recovery.

MMC erase is a concept very specific to flash memory. Magnetic disks have equal writing time whether they have data on them or whether they are blank. Also, the process for "erasing" a magnetic disk is to just write zeros over it. As a result, traditional formatting tools will just recreate a filesystem, leaving any existing data on the disk. If you want a privacy wipe, you overwrite the whole partition with zeros and/or random data. Prior to ICS, Android recoveries just did a basic filesystem format - which would leave any data still on the flash (just removing all pointers to it.)

With flash memory, there's a concept of "erased" vs. "holds data". To overwrite a block of flash, you must erase it first and then rewrite it. Modern flash disks (like eMMC) have built-in wear levellers that will, in many cases, take a block, read it, modify it, and write it somewhere new when the host system writes to a location. If the wear leveller has lots of pre-erased blocks to work with, write performance increases a bit.

So:

* Secure erase/TRIM - All physical blocks that are referenced by a given logical region of flash are erased, IN ADDITION to any physical blocks that were previously referenced but are just "lying around" - This process sometimes fails catastrophically on affected Samsung eMMc chips

* Nonsecure erase/TRIM - All physical blocks referenced by a given logical region are erased. "orphan" blocks aren't. Samsung claims this is safe - we've seen a few conflicting reports of this, but many of those turned out to be errors. For example, users fakeflashing CWM, wiping with it, but claiming they were on stock recovery because they started there. I'm nervous enough about this that right now, I don't permit it on any kernel I release. In theory, if done, this will lead to temporary write speed increases after a wipe until the wear leveller runs out of free blocks. Samsung's official patch they are deploying for this issue replaces secure erase with this form of erase

* "discard" - When mounted with this option, the filesystem can instruct the MMC driver to erase blocks that were related to a file when a file is deleted. As a result, the wear leveller should never run out of free blocks unless the flash fills up. No firmware I have ever seen for GS2-family devices has this mount option enabled. I'm a bit nervous about ever enabling it on affected devices

* Plain-old format - Leaves data still on disk, doesn't do a low-level hardware erase - The safest option that can still guarantee a "clean" uncorrupted filesystem. This is what a recovery format will do if the binary was built with BOARD_SUPPRESS_EMMC_WIPE or if the kernel has MMC_CAP_ERASE removed

* Recursive delete - If the filesystem is corrupted, it will remain corrupted/"unclean"