[[ssdbltrp]]
== "Ssdbltrp" Double Trap Extension, Version 1.0

The Ssdbltrp extension addresses a double trap (See <<machine-double-trap>>)
privilege modes lower than M. It enables HS-mode to invoke a critical error
handler in a virtual machine on a double trap in VS-mode. It also allows M-mode
to invoke a critical error handler in the OS/Hypervisor on a double trap in
S/HS-mode.

The Ssdbltrp extension adds the `menvcfg`.DTE (See <<sec:menvcfg>>) and the
`sstatus`.SDT fields (See <<sstatus>>). If the hypervisor extension is
additionally implemented, then the extension adds the `henvcfg`.DTE (See
<<sec:henvcfg>>) and the `vsstatus`.SDT fields (See <<vsstatus>>).

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