Section 2.5 describes how to extend the GDB command set. For the OpenRISC 1000 architecture, the info command is extended to show the value of SPRs (info spr) and a new command, spr is added to set the value of a SPR[2].
Both these commands are added in
_initialize_or1k_tdep
after the architecture has
been created and the disassembler automata initialized.
[2] There is a strong case for this being a new sub-command of the set. However the spr command was introduced in GDB 5.0, and there is no point in replacing it now.