Re: [PATCH 13/14] Pramfs: Write Protection

From: Marco Stornelli
Date: Thu Jun 18 2009 - 02:24:50 EST

2009/6/18 Paul Mundt <lethal@xxxxxxxxxxxx>:
> On Wed, Jun 17, 2009 at 06:58:00PM +0200, Marco wrote:
>> Jared Hulbert wrote:
>> > > Why not just fix flush_tlb_range()?
>> > >
>> > > If an arch has a flush_tlb_kernel_page() that works then it stands to
>> > > reason that the flush_tlb_kernel_range() shouldn't work with minimal
>> > > effort, no?
>> >
>> > flush_tlb_kernel_page() is a new one to me, it doesn't have any mention
>> > in Documentation/cachetlb.txt anyways.
>> >
>> > Many of the flush_tlb_kernel_range() implementations do ranged checks
>> > with tunables to determine whether it is more expensive to selectively
>> > flush vs just blowing the entire TLB away.
>> >
>> > Likewise, there is no reason why those 4 architectures can not just shove
>> > that if (end <= start + PAGE_SIZE) check in the beginning of their
>> > flush_tlb_kernel_range() and fall back on flush_tlb_kernel_page() for
>> > those cases. Hiding this in generic code is definitely not the way to go.
>> Ok I'll change that function at arch level and I'll remove the ifdef,
>> I'll call only flush_tlb_kernel_page(), but I'd like to know what is
>> the opinion of the arch maintainers to do that.  (Who is the maintainer
>> of H8300 arch?)
> No, you should call flush_tlb_kernel_range() and just fix up the
> flush_tlb_kernel_range() calls to wrap in to flush_tlb_kernel_page(). As
> far as the kernel is concerned, flush_tlb_kernel_page() is not a standard
> interface, as it has no mention in Documentation/cachetlb.txt.
> flush_tlb_page() and flush_tlb_kernel_range() on the other hand are both
> standard interfaces.

Oops, my fault. I meant flush_tlb_kernel_range not the page version,
sorry. I agree with you.

> H8300 is a nommu platform, so it has no TLB to flush. Yoshinori Sato is
> the maintainer. Consult the MAINTAINERS file, that's what it is there for.

I know the MAINTAINERS file but for h8300 there isn't an exactly
indication (/arch/h8300 as for the other archs).

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