* Toshi Kani <[email protected]> wrote:
> On Wed, 2015-02-18 at 21:44 +0100, Ingo Molnar wrote:
> > * Toshi Kani <[email protected]> wrote:
> >
> > > This patch implements huge I/O mapping capability interfaces on x86.
> >
> > > +#ifdef CONFIG_HUGE_IOMAP
> > > +#ifdef CONFIG_X86_64
> > > +#define IOREMAP_MAX_ORDER (PUD_SHIFT)
> > > +#else
> > > +#define IOREMAP_MAX_ORDER (PMD_SHIFT)
> > > +#endif
> > > +#endif /* CONFIG_HUGE_IOMAP */
> >
> > > +#ifdef CONFIG_HUGE_IOMAP
> >
> > Hm, so why is there a Kconfig option for this? It just
> > complicates things.
> >
> > For example the kernel already defaults to mapping itself
> > with as large mappings as possible, without a Kconfig entry
> > for it. There's no reason to make this configurable - and
> > quite a bit of complexity in the patches comes from this
> > configurability.
>
> This Kconfig option was added to disable this feature in
> case there is an issue. [...]
If bugs are found then they should be fixed.
> [...] That said, since the patchset also added a new
> nohugeiomap boot option for the same purpose, I agree
> that this Kconfig option can be removed. So, I will
> remove it in the next version.
>
> An example of such case is with multiple MTRRs described
> in patch 0/7.
So the multi-MTRR case should probably be detected and
handled safely?
Thanks,
Ingo
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