Add section for boot ROM reservations#30
Merged
Conversation
The boot ROM is allowed to use allocations of OCRAM as scratch space. If you interact with the boot ROM -- using it to interact with FlexSPI, for instance -- then you cannot also use these OCRAM regions. See the system boot chapter in the reference manual for more info. The boot ROM typically reserves the start of OCRAM. The size varies by chip. This commit describes a new section, .bootrom_reservation, at the start of OCRAM. Users are encouraged to place a MaybeUninit buffer that's sized for your ROM's requirements. If users don't place anything in this section, then the new directive is a no-op. On the other hand, the section is defined before other RAM regions, so that it takes precedence over other sections users might want to place in OCRAM. Tested using the runtime's test suite. I'm testing with the Teensy 4 binary, since the test suite can support features in this build. The updated test suite shows that the linker will place the boot ROM reservation before placing the stack, suggesting that we're respecting section priority.
This file contains hidden or 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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
The boot ROM is allowed to use allocations of OCRAM as scratch space. If you interact with the boot ROM -- using it to interact with FlexSPI, for instance -- then you cannot also use these OCRAM regions. See the system boot chapter in the reference manual for more info.
The boot ROM typically reserves the start of OCRAM. The size varies by chip. This commit describes a new section, .bootrom_reservation, at the start of OCRAM. Users are encouraged to place a MaybeUninit buffer that's sized for your ROM's requirements.
If users don't place anything in this section, then the new directive is a no-op. On the other hand, the section is defined before other RAM regions, so that it takes precedence over other sections users might want to place in OCRAM.
Tested using the runtime's test suite. I'm testing with the Teensy 4 binary, since the test suite can support features in this build. The updated test suite shows that the linker will place the boot ROM reservation before placing the stack, suggesting that we're respecting section priority.