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. 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. However, I believe it is very unlikely to have such platform/use-case, and it can also be avoided by a driver creating a separate mapping for each MTRR range. Thanks, -Toshi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
