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Re: semaphore woes in 2.6, 32bit

To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Subject: Re: semaphore woes in 2.6, 32bit
From: Ralf Baechle <ralf@linux-mips.org>
Date: Mon, 10 May 2004 16:06:06 +0200
Cc: geert@linux-m68k.org, jsun@mvista.com, linux-mips@linux-mips.org
In-reply-to: <20040510.222845.78701815.anemo@mba.ocn.ne.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20040509125750.GA19225@linux-mips.org> <20040509.225637.92590265.anemo@mba.ocn.ne.jp> <20040509164835.GA28011@linux-mips.org> <20040510.222845.78701815.anemo@mba.ocn.ne.jp>
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On Mon, May 10, 2004 at 10:28:45PM +0900, Atsushi Nemoto wrote:

> >> Hmm, many drivers use kmalloc and pci_map_single for DMA buffer.
> >> So ARCH_KMALLOC_MINALIGN should be L1_CACHE_BYTES for non-coherent
> >> system?
> 
> ralf> No, those drivers are simply broken.  dma_get_cache_alignment()
> ralf> gives the mimimum alignment and width for DMA mappings and that
> ralf> value is larger than kmalloc alignment in almost all cases.
> 
> I see.  Thank you for pointing out it.  I must learn 2.6 DMA API
> quickly ...

This also applies to the 2.4 PCI DMA API.

  Ralf

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