[bazel, qemu] Implement QEMU Rescue 1.0 (Serial Break) & RESET strapping #28449
Conversation
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
AlexJones0
requested review from
jwnrt,
pamaury and
ziuziakowska
and removed request for
a team and
cfrantz
AlexJones0
force-pushed
the
qemu_uart_rescue
branch
from
7dfc0cc to
c416d31
Compare
These will be required to support using break for Serial Rescue 1.0 in the ROM_EXT, as we need to mock values in the oversampled UART `VAL` register based upon the transmission of break conditions via the QEMU monitor, which when received are controlled by these properties. Signed-off-by: Alex Jones <[email protected]>
If any QEMU devices need to hold a reference to the QEMU monitor then dropping the QEMU transport could result in the monitor being used to quit QEMU before the devices can cleanup on drop. Instead, quit QEMU via the monitor when dropping the Monitor. Signed-off-by: Alex Jones <[email protected]>
Some commands might need to supply optional arguments as some JSON serialized string. Add an optional `arguments` field to the QEMU Monitor's `send_cmd` function that supports this functionality. Signed-off-by: Alex Jones <[email protected]>
This command can be used to send a UART break condition to a CharDev identified by a given identifier. Signed-off-by: Alex Jones <[email protected]>
TO support the requires use of Serial Break for rescue via reading the UART's oversampled `VAL` register in the ROM_EXT, introduce a mechanism that uses the QEMU monitor to send break conditions to the UART, which are subsequently tracked by the QEMU UART device to mock the required behaviour. Signed-off-by: Alex Jones <[email protected]>
Signed-off-by: Alex Jones <[email protected]>
This commit only includes the non-ownership (activate, unlock) tests, as the ownership tests are separated due to their need for more complicated test infrastructure. All tests are supported and passing in QEMU with the exception of the `boot_service_wakeup` test, which is not expected to work, as QEMU's pwrmgr currently does not model low power entry/exit. Signed-off-by: Alex Jones <[email protected]>
AlexJones0
force-pushed
the
qemu_uart_rescue
branch
from
c416d31 to
c4bff2b
Compare
|
This has a full passing QEMU CI regression run as well: https://github.com/lowRISC/qemu/actions/runs/18319254765 |
jwnrt
approved these changes
Oct 9, 2025
6 tasks
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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.
See the commit messages for more details - these PRs introduce the relevant opentitantool support for the
RESETstrapping used by tests (which already existed but just was not defined in the JSON file), and more importantly implements UART RX break for QEMU via the QEMU monitor to allow use of Rescue 1.0 (Serial Break) flows. This is particularly important for e.g. emulating ownership transfer flows via UART.Note that the implementation of break goes through the QEMU Monitor and not the UART due to QEMU's lack of break support on different CharDev types. Also note that we use a custom implementation on top of these break events to support the toggling of RX break so that we can hold it down like a strap, as the ROM_EXT rescue protocol relies on reading the UART oversampling register to be able to detect serial breaks as rescue like a strap. See more relevant discussion here: lowRISC/qemu#212
To test that this works, this PR implements QEMU environments for all E2E boot service tests (not including ownership transfer, which is separate), except for the
boot_service_wakeuptest which is not expected to pass because of lacking low power entry/exitpwrmgremulation in QEMU.