Re: [PATCH 3/9] x86/moorestown: add moorestown platform flags

From: Ingo Molnar
Date: Fri Jun 26 2009 - 08:23:23 EST



* Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:

> > > The flags are passed by the boot loader which is the one thing
> > > that knows what the platform is only deeply embedded hardware. See
> > > the ARM and PPC ports.
> >
> > And? There's an obvious quality difference between various
> > platform enumeration methods - and we strive for the highest
> > quality methods.
>
> Good the boot loader knows precisely what it is running on

That's a pretty bogus claim - on x86 a bootloader generally knows
very little about 'what it is running on'. We do most of the
enumeration in early platform code and retrieve information via
standard BIOS interfaces.

> > Using boot flags is one of the lowest quality enumeration
> > methods
>
> It's probably the most reliable. If you don't believe so then
> provide data to back your assertion

You are the one who is trying to do a change here really, so you
should provide data to back your assertion that all existing x86
enumeration methods are wrong and that modern x86 platforms from
now on should freely splinter into non-standard platforms along
boot flags.

The success of the PC platform was based on standardization and
standard interfaces. Do you need data for that fact? ;-)

> > and the fact that there's precedence for it in other
> > architectures is not a technical reason to make the same
> > mistakes on x86 too.
>
> How about "they tried other methods and they didn't work"

The thing is, you are trying to defend a v1 patch-set here that is
really indefensible: it's ugly and deficient in numerous smaller and
larger details. I outlined numerous deficiencies already - and i'll
review v2 too to see what else is there to fix.

You outlined here various claims about how x86 should suddenly
change into ARM or PPC to become 'successful' - but if this current
patch-set is your attempt at that then it has failed spectacularly.

Thanks,

Ingo
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