From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Andreas Schwab <schwab@suse.de>
Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: pte_offset_map for ppc assumes HIGHPTE
Date: Thu, 26 Jul 2007 09:22:45 +1000 [thread overview]
Message-ID: <1185405765.5439.371.camel@localhost.localdomain> (raw)
In-Reply-To: <jewswodqcn.fsf@sykes.suse.de>
On Thu, 2007-07-26 at 01:18 +0200, Andreas Schwab wrote:
> Satya <satyakiran@gmail.com> writes:
>
> > hello,
> > The implementation of pte_offset_map() for ppc assumes that PTEs are
> > kept in highmem (CONFIG_HIGHPTE). There is only one implmentation of
> > pte_offset_map() as follows (include/asm-ppc/pgtable.h):
> >
> > #define pte_offset_map(dir, addr) \
> > ((pte_t *) kmap_atomic(pmd_page(*(dir)), KM_PTE0) + pte_index(addr))
> >
> > Shouldn't this be made conditional according to CONFIG_HIGHPTE is
> > defined or not
>
> kmap_atomic is always defined with or without CONFIG_HIGHPTE.
>
> > (as implemented in include/asm-i386/pgtable.h) ?
>
> I don't think that needs it either.
Depends... if you have CONFIG_HIGHMEM and not CONFIG_HIGHPTE, you are wasting
time going through kmap_atomic unnecessarily no ? it will probably not do anything
because the PTE page is in lowmem but still...
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Andreas Schwab <schwab@suse.de>
Cc: Satya <satyakiran@gmail.com>,
linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: pte_offset_map for ppc assumes HIGHPTE
Date: Thu, 26 Jul 2007 09:22:45 +1000 [thread overview]
Message-ID: <1185405765.5439.371.camel@localhost.localdomain> (raw)
In-Reply-To: <jewswodqcn.fsf@sykes.suse.de>
On Thu, 2007-07-26 at 01:18 +0200, Andreas Schwab wrote:
> Satya <satyakiran@gmail.com> writes:
>
> > hello,
> > The implementation of pte_offset_map() for ppc assumes that PTEs are
> > kept in highmem (CONFIG_HIGHPTE). There is only one implmentation of
> > pte_offset_map() as follows (include/asm-ppc/pgtable.h):
> >
> > #define pte_offset_map(dir, addr) \
> > ((pte_t *) kmap_atomic(pmd_page(*(dir)), KM_PTE0) + pte_index(addr))
> >
> > Shouldn't this be made conditional according to CONFIG_HIGHPTE is
> > defined or not
>
> kmap_atomic is always defined with or without CONFIG_HIGHPTE.
>
> > (as implemented in include/asm-i386/pgtable.h) ?
>
> I don't think that needs it either.
Depends... if you have CONFIG_HIGHMEM and not CONFIG_HIGHPTE, you are wasting
time going through kmap_atomic unnecessarily no ? it will probably not do anything
because the PTE page is in lowmem but still...
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Andreas Schwab <schwab@suse.de>
Cc: Satya <satyakiran@gmail.com>,
linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: pte_offset_map for ppc assumes HIGHPTE
Date: Thu, 26 Jul 2007 09:22:45 +1000 [thread overview]
Message-ID: <1185405765.5439.371.camel@localhost.localdomain> (raw)
In-Reply-To: <jewswodqcn.fsf@sykes.suse.de>
On Thu, 2007-07-26 at 01:18 +0200, Andreas Schwab wrote:
> Satya <satyakiran@gmail.com> writes:
>
> > hello,
> > The implementation of pte_offset_map() for ppc assumes that PTEs are
> > kept in highmem (CONFIG_HIGHPTE). There is only one implmentation of
> > pte_offset_map() as follows (include/asm-ppc/pgtable.h):
> >
> > #define pte_offset_map(dir, addr) \
> > ((pte_t *) kmap_atomic(pmd_page(*(dir)), KM_PTE0) + pte_index(addr))
> >
> > Shouldn't this be made conditional according to CONFIG_HIGHPTE is
> > defined or not
>
> kmap_atomic is always defined with or without CONFIG_HIGHPTE.
>
> > (as implemented in include/asm-i386/pgtable.h) ?
>
> I don't think that needs it either.
Depends... if you have CONFIG_HIGHMEM and not CONFIG_HIGHPTE, you are wasting
time going through kmap_atomic unnecessarily no ? it will probably not do anything
because the PTE page is in lowmem but still...
Ben.
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next prev parent reply other threads:[~2007-07-25 23:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-25 22:16 pte_offset_map for ppc assumes HIGHPTE Satya
2007-07-25 22:16 ` Satya
2007-07-25 23:10 ` Benjamin Herrenschmidt
2007-07-25 23:10 ` Benjamin Herrenschmidt
2007-07-25 23:10 ` Benjamin Herrenschmidt
2007-07-25 23:18 ` Andreas Schwab
2007-07-25 23:18 ` Andreas Schwab
2007-07-25 23:18 ` Andreas Schwab
2007-07-25 23:22 ` Benjamin Herrenschmidt [this message]
2007-07-25 23:22 ` Benjamin Herrenschmidt
2007-07-25 23:22 ` Benjamin Herrenschmidt
2007-07-25 23:30 ` Dave McCracken
2007-07-25 23:30 ` Dave McCracken
2007-07-25 23:30 ` Dave McCracken
2007-07-26 0:18 ` Benjamin Herrenschmidt
2007-07-26 0:18 ` Benjamin Herrenschmidt
2007-07-26 0:18 ` Benjamin Herrenschmidt
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