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From: Robert Watson <rwatson@FreeBSD.org>
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To: Marcel Moolenaar <marcel@FreeBSD.org>
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Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org,
	src-committers@freebsd.org
Subject: Re: svn commit: r198451 - head/sys/ia64/include
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On Sat, 24 Oct 2009, Marcel Moolenaar wrote:

> Log:
>  A 32KB kernel stack is not quite enough. The new USB stack is a bit
>  more stack hungry as compared to the old one that my RX2660 gets
>  a machine check and spontaneously reboots at the time the USB DVD
>  drive is found and attached to CAM as a mass storage device. This
>  doesn't happen always, but definitely varies per kernel build.
>  Likewise when using a 128-byte printf buffer. The additional 128
>  bytes that printf needs seems to be enough to have the memory stack
>  and register stack collide and causing a machine check.

I recently noticed, somewhat to my surprise, that BPF drops a 512-byte buffer 
on the stack while running filters...

Robert

>
>  Thus: Bump KSTACK_PAGES from 4 to 5.
>
> Modified:
>  head/sys/ia64/include/param.h
>
> Modified: head/sys/ia64/include/param.h
> ==============================================================================
> --- head/sys/ia64/include/param.h	Sat Oct 24 20:07:17 2009	(r198450)
> +++ head/sys/ia64/include/param.h	Sat Oct 24 20:28:42 2009	(r198451)
> @@ -92,7 +92,7 @@
> #define	MAXPAGESIZES	1		/* maximum number of supported page sizes */
>
> #ifndef	KSTACK_PAGES
> -#define	KSTACK_PAGES	4		/* pages of kernel stack */
> +#define	KSTACK_PAGES	5		/* pages of kernel stack */
> #endif
> #define	KSTACK_GUARD_PAGES 0		/* pages of kstack guard; 0 disables */
>
>