Re: [RFC][PATCH] linux-2.6.3-rc2_ia64-cyclone_A0

From: john stultz <>
Date: 2004-02-13 12:05:50
On Thu, 2004-02-12 at 16:14, David Mosberger wrote:
> >>>>> On Wed, 11 Feb 2004 19:22:21 -0800, john stultz <> said:
>   John> All, This patch provides access to the cyclone time source
>   John> found on IBM EXA based systems (x450 and x455). This is needed
>   John> on multi-node systems where the CPU ITCs are not synchronized,
>   John> causing possible time inconsistencies.
>   John> I tried my best to properly follow the time_interpolator
>   John> interface, but please let me know if you see any mistakes.
>   John> Any comments or suggestions would be greatly appreciated.
> It looks mostly OK to me.  Some comments:
>  - It seems to me cyclone.c should check whether the SAL ITCdrift flag
>    is on and register the cyclone time-interpolator only if it is
>    turned on.

Hmm. As cyclone is only enabled for x450/x455 systems, I'm not sure if
that additional check is necessary, but I'll try to look into that.

>  - When accessing iomemory space, please use readX()/writeX().  For
>    example:
>  +	offset = cyclone_timer[0];
>    should be:
> 	offset = readl (cyclone_timer);

Ok, will fix. 

>  - The formatting is a bit weird.  You can format it for 100 columns
>    wide and it would be nice if you could drop all the trailing
>    whitespace.

Gah! Sorry, I'm terrible w/ whitespace.

>  - This:
> +	u32 offset;
> 	  [snip]
> +	offset = (offset*NSEC_PER_SEC)/CYCLONE_TIMER_FREQ;
>    will overflow in about 4.3 seconds.  Not likely to happen but
>    it might be safer to declare "offset" as "u64".

Yep, I caught that right after I sent out the patch. 

Thanks so much for the review! I'll apply your suggestions and resend.

thanks again,

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Received on Thu Feb 12 20:08:44 2004

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