Toboot must clear entire application area about toboot HOT 10 CLOSED

This functionality was implemented in API v2.0.

from toboot.

@xobs - FYI

from toboot.

We don't clear the entire application area for a number of reasons. First, we're not sure what's application and what's data. An application may want to save configuration data across firmware versions.

The proposed solution is to set the Configuration Value to disable the Toboot short-to-enter ability. Then when a user wants to update, the U2F program should clear its own keys, set the magic value, and reboot. That way an application can determine what areas to erase and what to keep.

from toboot.

OK. Then I need to come up with a good way to tell U2F firmware to reset itself. I think it may even be the same "short-at-boot"...

from toboot.

Second thought. What if we add another magic value to indicate that entering into bootloader via shorting pads should erase application area. I think there must be a way to get to bootloader even from locked device and adding it to application just makes things more complex and creates duplication of code and features. If we agree on that I volunteer to implement this feature.

from toboot.

Changed u2f firmware to

1. turn off toboot short-to-boot feature
2. added short-to-reset feature to erase secret keys and unlock toboot

im-tomu/chopstx@7aed937

There is now build option (turned off by default) to make u2f firmware to debug-lock the board on first start. It is not on by default because J Link required to unlock device.

Still I would happily throw this patch away if toboot allowed to erase application area.

from toboot.

The v2.0 API includes a 64-bit mask field in the header that allows you to request sectors to be erased. Is that sufficient to implement this request?

from toboot.

I guess yes. Just to make sure. If pages are erased during update, will toboot get the bitmask from the newly loaded program, or from the previous one?

from toboot.

It reads it from the previous image.

Toboot determines what the previous image is by looking at all blocks on the system and selecting the valid header that has the highest "generation" value. It will use that as an image to boot to.

Additionally, when performing an update it will use the existing header as a guideline for what blocks to erase. If you want to erase everything (except Toboot itself), set the value to 0xffffffff ffffffff.

from toboot.

Sounds good! Thank you for implementing that!

from toboot.