KD supports multiple processor debugging. Processors are numbered 0 through n.
If the current processor is processor 0 (that is, if it is processor 0 that currently causes KD to be active), you can look at the other noncurrent processors (processors 1 through n). However, you cannot change anything in the noncurrent processors; you can only look at their state. For example, you can run k and r commands on other processors, using "1r" to dump the registers of processor 1, and "2k" to do a stack trace on processor 2, etc. But running "1r eax=8080808" gives a syntax error because changing the state of noncurrent processors is not allowed.
The KD commands ba, (not implemented on MIPS or PowerPC) and bp apply to all processors of a multiple processor computer. For example, if the current processor is 63 and you type
bp SomeAddress
to put a breakpoint at SomeAddress, any processor (not just processor 63) executing at that address will cause a breakpoint trap.