[[smdbltrp]]
== "Smdbltrp" Double Trap Extension, Version 1.0

The Smdbltrp extension addresses a double trap (See <<machine-double-trap>>) in
M-mode. When the Smrnmi extension (<<rnmi>>) is implemented, it enables
invocation of the RNMI handler on a double trap in M-mode to handle the
critical error. If the Smrnmi extension is not implemented or if a double trap
occurs during the RNMI handler's execution, this extension helps transition the
hart to a critical error state and enables signaling the critical error to the
platform.

To improve error diagnosis and resolution, this extension supports debugging
harts in a critical error state. The extension introduces a mechanism to enter
Debug Mode instead of asserting a critical-error signal to the platform when the
hart is in a critical error state. See cite:[DEBUG_SPEC] for details.

See <<machine-double-trap>> for the operational details.