On Út 28-02-06 23:33:53, Dave Jones wrote:
> On Wed, Mar 01, 2006 at 02:57:05PM +1100, Michael Ellerman wrote:
> > On 1/20/06, Darrick J. Wong <[email protected]> wrote:
> > > Hi there,
> > >
> > > Some old i386 systems have flaky APIC hardware that doesn't always work
> > > right. Right now, enabling the APIC code in Kconfig means that the APIC
> > > code will try to activate the APICs unless 'noapic nolapic' are passed
> > > to force them off. The attached patch provides a config option to
> > > change that default to keep the APICs off unless specified otherwise,
> > > disables get_smp_config if we are not initializing the local APIC, and
> > > makes init_apic_mappings not init the IOAPICs if they are disabled.
> > > Note that the current behavior is maintained if
> > > CONFIG_X86_UP_APIC_DEFAULT_OFF=n.
> > Did this hit the floor?
>
> It's still being kicked around. I saw one patch off-list earlier this
> week that has some small improvements over the variant originally posted,
> but still had 1-2 kinks.
>
> > It strikes me as a pretty good solution. This
> > is pretty nasty for newbies installing distro kernels, they get some
> > of the way through an install and then their machine just locks - not
> > good PR.
>
> The number of systems that actually *need* APIC enabled are in the
> vast (though growing) minority, so it's unlikely that most newbies
> will hit this. The problem is also the inverse of what you describe.
> Typically the distros have DMI lists of machines that *need* APIC
> to make it enabled by default so everything 'just works'.
Well, blacklisting "new" machines is a problem -- their number
grows. Would not it be better to blacklist machines broken by APIC
("old" ones, presumably)?
> The big problem the patch solves is allowing it to be possible
> to build a kernel with UP APIC code, but disabled by default
> (Because there a lot of older machines that die horribly if it
> was enabled by default).
Is adding "noapic nolapic" to default command line a big problem?
Pavel
--
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