Date: Thu, 25 Jul 2002 16:45:21 -0700 (PDT)
From: Andre Hedrick <andre@linux-ide.org>
To: "Charles R. Anderson" <cra@WPI.EDU>
cc: linux-kernel@vger.kernel.org
Subject: Re: 2.4.19-rc3-ac3 ide_map_buffer/ide_unmap_buffer
In-Reply-To: <20020725193806.U7778@angus.ind.WPI.EDU>
Message-ID: <Pine.LNX.4.10.10207251644380.4719-100000@master.linux-ide.org>
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Well there is a clash of patchs and both are needed, and the have to be
mixed to gather properly.

On Thu, 25 Jul 2002, Charles R. Anderson wrote:

> [I'm not subscribed, so please Cc: me directly.  Thanks.]
> 
> patch-2.4.19-rc3-ac3 has this stuff related to highmem support:
> 
>  /*
> + * mapping stuff, prepare for highmem...
> + * 
> + * temporarily mapping a (possible) highmem bio for PIO transfer
> + */
> +#define ide_rq_offset(rq) \
> +       (((rq)->hard_cur_sectors - (rq)->current_nr_sectors) << 9)
> +
> +extern inline void *ide_map_buffer(struct request *rq, unsigned long
> *flags)
> +{
> +       return rq->buffer + ide_rq_offset(rq);
> +}
> +
> +extern inline void ide_unmap_buffer(char *buffer, unsigned long *flags)
> +{
> +       do { } while (0);
> +}
> 
> Red Hat's 2.4.18-5 kernel has these conflicting bits in
> linux-2.4.17-blockhighmem.patch:
> 
> +
> +/*
> + * temporarily mapping a (possible) highmem bio
> + */
> +#define ide_rq_offset(rq) (((rq)->hard_cur_sectors - (rq)->current_nr_sectors) << 9)
> +
> +extern inline void *ide_map_buffer(struct request *rq, unsigned long
> *flags)
> +{
> +       return bh_kmap_irq(rq->bh, flags) + ide_rq_offset(rq);
> +}
> +
> +extern inline void ide_unmap_buffer(char *buffer, unsigned long *flags)
> +{
> +       bh_kunmap_irq(buffer, flags);
> +}
> 
> Which one should I apply? I'm inclined to keep the Red Hat bits, since
> the ac3 ide_unmap_buffer does nothing.
> 
> [For anyone wondering, I have a new Dell with an Intel 845G chipset for
> which I would like DMA support, etc.  I'm attempting to merge
> 2.4.19-rc3-ac3 with Red Hat's patches.  If anyone has a simple patch for
> 82801DB IDE DMA support which applies to 2.4.18 I'd be much obliged.]
> 
> Thanks.
> 
> -- 
> Charles R. Anderson <cra@wpi.edu> / http://angus.ind.wpi.edu/~cra/
> PGP Key ID: 49BB5886
> Fingerprint: EBA3 A106 7C93 FA07 8E15  3AC2 C367 A0F9 49BB 5886
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> 

Andre Hedrick
LAD Storage Consulting Group

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