sw: Fix RAM boot detection #331
Open
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Up until now, docs said that RAM boot happens, when foboot finds `0x17ab0f23` in first 56 bytes of loaded binary. That wasn't the case, it was checking only first 12 bytes. `for` loop did at most `(max_check/4)-1` iterations, which is equal to 15, because `max_check` has the value of `rx_buffer` size from usb-dev.c. 15 times 4 byte words results in 60 checked bytes, but there was also division by 4 when accessing items of `dfu_buffer`, which reduced number of checks to 3. I also corrected the docs from 56 checked bytes to 60.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Up until now, docs said that RAM boot happens, when foboot finds
0x17ab0f23in first 56 bytes of loaded binary.That wasn't the case, it was checking only first 12 bytes.
forloop did at most(max_check/4)-1iterations, which is equal to 15, becausemax_checkhas the value ofrx_buffersize from usb-dev.c, which is 64 bytes.15 times 4 byte words results in 60 checked bytes, but there was also division by 4 when accessing items of
dfu_buffer, which reduced number of checks to 3 resulting in 12 bytes checked.I also corrected the docs from 56 checked bytes to 60.