From: Catalin Marinas <catalin.marinas@arm.com>
To: Pingfan Liu <kernelfans@gmail.com>
Cc: Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64/fixmap: make notes of fixed_addresses more precisely
Date: Fri, 31 Jul 2020 13:13:35 +0100 [thread overview]
Message-ID: <20200731121334.GC29569@gaia> (raw)
In-Reply-To: <CAFgQCTv3L-xYxHCGtm9qEGUxGUnL+fncKtvMgsssd4A52P6DVA@mail.gmail.com>
On Fri, Jul 31, 2020 at 10:47:13AM +0800, Pingfan Liu wrote:
> On Thu, Jul 30, 2020 at 7:09 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Fri, Jul 10, 2020 at 09:43:22PM +0800, Pingfan Liu wrote:
> > > These 'compile-time allocated' memory buffers can occupy more than one
> > > page. So improve the note about it.
> > >
> > > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > Cc: Will Deacon <will@kernel.org>
> > > To: linux-arm-kernel@lists.infradead.org
> > > ---
> > > arch/arm64/include/asm/fixmap.h | 3 ++-
> > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h
> > > index f987b8a..318aee1 100644
> > > --- a/arch/arm64/include/asm/fixmap.h
> > > +++ b/arch/arm64/include/asm/fixmap.h
> > > @@ -29,7 +29,8 @@
> > > * in the boot process.
> > > *
> > > * These 'compile-time allocated' memory buffers are
> > > - * page-sized. Use set_fixmap(idx,phys) to associate
> > > + * page-sized (or larger if used with an increment
> > > + * higher than 1). Use set_fixmap(idx,phys) to associate
> > > * physical memory with fixmap indices.
> >
> > I don't get this. set_fixmap() only maps a page. Also, what's
> > "increment" in this context?
>
> I refer to the notes in the counterpart in x86. And for the time
> being, it is the case for the ranges (FIX_FDT, FIX_FDT_END), which may
> cost more than one page size.
OK, so increment refers to the enum increment. But if we update this, we
also need to state that set_fixmap() only maps page-size buffers,
otherwise one may think that set_fixmap(FIX_FDT, phys) maps the whole
FDT. We could say that each enum increment represents a page-sized
buffer.
--
Catalin
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next prev parent reply other threads:[~2020-07-31 12:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 13:43 [PATCH] arm64/fixmap: make notes of fixed_addresses more precisely Pingfan Liu
2020-07-30 11:09 ` Catalin Marinas
2020-07-31 2:47 ` Pingfan Liu
2020-07-31 12:13 ` Catalin Marinas [this message]
2020-08-03 2:07 ` Pingfan Liu
2020-08-03 11:53 ` Catalin Marinas
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