Palcode-OS Exception interface

[Martin Husemann <martin%duskware.de@localhost>]

Does anyone here happen to know what document describes the palcode<->OS
exception interface?

Looking at alpha/trap.c:326 it seems that the variable "ucode" is used
unintialized for ALPHA_KENTRY_IF calls, and the whole
alpha_ucode_to_ksiginfo() call probably does not make sense here, but
the arguments to the trap() call come straight from pal (via
PALVECT(XentIF) in locore.s) - and I would like to understand a0 - a2.

Martin