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Date: Wed, 22 Feb 2006 09:49:17 +0100
From: Jens Axboe <qemu@kernel.dk>
Subject: Re: [Qemu-devel] [PATCH] Fix Harddisk initialization
Message-ID: <20060222084917.GO8852@suse.de>
References: <20060221192928.GD4110@networkno.de>
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To: qemu-devel@nongnu.org

On Tue, Feb 21 2006, Thiemo Seufer wrote:
> Hello All,
> 
> this fixes Harddisk initialization (s->nsector is initially 0x100, which
> is supposed to get handled as zero).
> 
> 
> Thiemo
> 
> 
> Index: qemu-work/hw/ide.c
> ===================================================================
> --- qemu-work.orig/hw/ide.c	2006-02-18 22:12:56.000000000 +0000
> +++ qemu-work/hw/ide.c	2006-02-19 02:34:13.000000000 +0000
> @@ -1550,12 +1550,12 @@
>              ide_set_irq(s);
>              break;
>          case WIN_SETMULT:
> -            if (s->nsector > MAX_MULT_SECTORS || 
> +            if ((s->nsector & 0xFF) > MAX_MULT_SECTORS ||
>                  s->nsector == 0 ||
>                  (s->nsector & (s->nsector - 1)) != 0) {
>                  ide_abort_command(s);
>              } else {
> -                s->mult_sectors = s->nsector;
> +                s->mult_sectors = s->nsector & 0xFF;
>                  s->status = READY_STAT;
>              }
>              ide_set_irq(s);

I think the much better patch would be to fix qemu not to put 256
unconditionally in ->nsector if it is written as zero. It's really a
special case for only the read/write commands, not a generel fixup.
I'd suggest adding a nsector_internal to fixup this internally in the
read/write path so all register correctly reflect what was actually
written by the OS.

-- 
Jens Axboe