Re: [patch 1/3] kdump: use is_kdump_kernel() in sba_init()

[Vivek Goyal <vgoyal@redhat.com>]

On Tue, Jul 29, 2008 at 06:12:36PM +1000, Simon Horman wrote:
> After recent patches* is_kdump_kernel() should return 1 in the
> case where code is executing in a crashkernel and 0 otherwise.
> It is save to use outside of CONFIG_KDUMP.
> 
> * http://lkml.org/lkml/2008/7/28/445
> 

Hi Simon,

is_kdump_kernel() returns 1 when both the following conditions are true.

- CONFIG_CRASH_DUMP is enabled
- And kernel is booting after a panic.

If any of the above condition is not true, it returns 0.

So for the cases where, CONFIG_CRASH_DUMP=n and kernel is booting after
panic, is_kdump_kernel() will still return 0.

This essentially means that any kernel which is booting after a panic,
but does not have CONFIG_CRASH_DUMP enabled, will not take special actions
required for booting that kernel. Until, somebody can come up with another
usage of booting a kernel after a panic (apart from crash dump), I think
this is good enough an assumption.

So your changes will work. I just wanted to clarify the semantics more
explicitly.

> Signed-off-by: Simon Horman <horms@verge.net.au>
> 
> 
> Index: linux-2.6/arch/ia64/hp/common/sba_iommu.c
> =================================> --- linux-2.6.orig/arch/ia64/hp/common/sba_iommu.c	2008-07-29 10:57:17.000000000 +1000
> +++ linux-2.6/arch/ia64/hp/common/sba_iommu.c	2008-07-29 10:57:51.000000000 +1000
> @@ -2070,14 +2070,13 @@ sba_init(void)
>  	if (!ia64_platform_is("hpzx1") && !ia64_platform_is("hpzx1_swiotlb"))
>  		return 0;
>  
> -#if defined(CONFIG_IA64_GENERIC) && defined(CONFIG_CRASH_DUMP) && \
> -        defined(CONFIG_PROC_FS)
> +#if defined(CONFIG_IA64_GENERIC)


Acked-by: Vivek Goyal <vgoyal@redhat.com>

Thanks
Vivek