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From: Russell King <rmk@arm.linux.org.uk>
To: Andrew Morton <akpm@digeo.com>, David Miller <davem@redhat.com>,
	Paul Mackerras <paulus@samba.org>,
	linux-kernel@vger.kernel.org,
	linuxppc-embedded@lists.linuxppc.org
Subject: Re: [PATCH,RFC] Add gfp_mask to get_vm_area()
Date: Tue, 1 Oct 2002 09:42:02 +0100	[thread overview]
Message-ID: <20021001094202.C29814@flint.arm.linux.org.uk> (raw)
In-Reply-To: <20021001053417.GW10265@zax>; from david@gibson.dropbear.id.au on Tue, Oct 01, 2002 at 03:34:17PM +1000

On Tue, Oct 01, 2002 at 03:34:17PM +1000, David Gibson wrote:
> I don't see an easy one: PPC 4xx has non-coherent cache, so we have to
> mark consistent memory non-cacheable.  We want to make the normal
> lowmem mapping use large page TLB entries, so we can't frob the
> attribute bits on the pages in place.  That means we need to create a
> new, non-cacheable mapping for the physical RAM we allocate, which in
> turn means allocating a chunk of kernel virtual memory.

Same problem on ARM.  I just haven't got the motivation to rewrite the
bits of the kernel that need to be rewritten to make it work.

Have you checked that your pte/pmd allocation functions can be called
from IRQ context as well?

You basically need:

 - irq-safe get_vm_area
 - irq-safe pmd_alloc_kernel
 - irq-safe pte_alloc_kernel

Last time I looked, all the above were not irq-safe.

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html


  reply	other threads:[~2002-10-01  8:36 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-10-01  4:42 [PATCH,RFC] Add gfp_mask to get_vm_area() David Gibson
2002-10-01  4:37 ` David S. Miller
2002-10-01  5:08 ` Andrew Morton
2002-10-01  5:34   ` David Gibson
2002-10-01  8:42     ` Russell King [this message]
2002-10-02  1:18       ` David Gibson
2002-10-03  4:39     ` David Gibson
2002-10-03  4:56       ` David Gibson
2002-10-03 15:18         ` Russell King
2002-10-04  3:27           ` David Gibson

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