Subject: Re: Math instruction emulation in KA660 VAX 4200 cpu?
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: port-vax
Date: 05/07/2003 02:00:33
> Does the KA660 VAX 4000 200 cpu need the math instruction emulation
> in the kernel config or can that non-emulation option be turned on?

> p.s. what about same on the KA630 and KA650 cpu's?

I know the KA630 depends on software emulation for many instructions,
at least a few of which are necessary for normal operation.

But, what "math instruction emulation" is this?  The closest thing I
see in GENERIC,v 1.113 is NO_INSN_EMULATE, which covers very little I
would class as "math", covering instead packed decimal arithmetic and
conversions and the more complex of the string instructions (which
former may be what you call "math instruction[s]") and a few miscellany
like crc.  intvec.S includes a table of emulated instructions;
unfortunately, there is no indication whether the holes in this table
(un-emulated opcodes) have gone unemulated because they are opcodes the
CPU doesn't trap on or because they're opcodes that no emulation has
been written for.  It certainly includes many of the former (0x04=ret,
0x05=rsb, 0x06=ldpctx, etc); I find no examples of the latter on a
quick look, but it's possible there are instances of the latter that
fall outside the table there - or that I missed something.

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