Re: [RFC] Design considerations for XSAVE Extended Area getters/setters

[Michał Górny <mgorny%NetBSD.org@localhost>]

On Tue, 2019-05-28 at 19:37 +0200, Martin Husemann wrote:
> Stupid question: since this is all very rare and non-performance critical,
> why isn't it done as a single register per call? Adding more registers
> when thy arrive in newer cpu variants, and not worrying about how they
> are saved (XSAVE or similar) nor what format is used in the kernel?
> 
> So a debugger would do a single PT_GETREG_$REGISTER call from userland
> for each register it is interested in. The current state with register
> groups (regs, fpregs, dbregs, xmmmregs, vecregs, ...) looks like a hack
> to me.
> 
> The first two make some sense (across various cpu architectures), and
> maybe performance and debug registers could be a third reasonable group
> (especially given the security implications), but everything else is
> arbitrary and may just as well be individual registers.
> 

Well, if we are only to consider new registers, then we're talking about
16 'pure' ymm registers + 32 zmm registers + 8 kN registers + 1 state
register, multiply by two... 114 PT_* requests?

-- 
Best regards,
Michał Górny