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From: Vivek Goyal <vgoyal@redhat.com>
To: Simon Horman <horms@verge.net.au>
Cc: linux-ia64@vger.kernel.org, kexec@lists.infradead.org,
	lkml@vger.kernel.org
Subject: Re: [patch 1/3] kdump: use is_kdump_kernel() in sba_init()
Date: Tue, 29 Jul 2008 10:51:56 -0400	[thread overview]
Message-ID: <20080729145156.GO25975@redhat.com> (raw)
In-Reply-To: <20080729081629.356523305@vergenet.net>

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

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kexec@lists.infradead.org
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WARNING: multiple messages have this Message-ID (diff)
From: Vivek Goyal <vgoyal@redhat.com>
To: Simon Horman <horms@verge.net.au>
Cc: linux-ia64@vger.kernel.org, kexec@lists.infradead.org,
	lkml@vger.kernel.org
Subject: Re: [patch 1/3] kdump: use is_kdump_kernel() in sba_init()
Date: Tue, 29 Jul 2008 14:51:56 +0000	[thread overview]
Message-ID: <20080729145156.GO25975@redhat.com> (raw)
In-Reply-To: <20080729081629.356523305@vergenet.net>

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

  reply	other threads:[~2008-07-29 14:51 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20080729081235.293361145@vergenet.net>
2008-07-29  8:12 ` [patch 1/3] kdump: use is_kdump_kernel() in sba_init() Simon Horman
2008-07-29  8:12   ` Simon Horman
2008-07-29 14:51   ` Vivek Goyal [this message]
2008-07-29 14:51     ` Vivek Goyal
2008-07-29 22:40     ` Simon Horman
2008-07-29 22:40       ` Simon Horman
2008-07-29 22:40       ` Simon Horman
2008-07-29 23:15   ` Simon Horman
2008-07-29 23:15     ` Simon Horman
2008-07-29 23:15     ` Simon Horman
2008-07-30 12:55     ` Vivek Goyal
2008-07-30 12:55       ` Vivek Goyal
2008-07-30 12:55       ` Vivek Goyal
2008-07-29  8:12 ` [patch 2/3] kdump: add is_vmcore_usable() and vmcore_unusable() Simon Horman
2008-07-29  8:12   ` Simon Horman
2008-07-29 15:15   ` Vivek Goyal
2008-07-29 15:15     ` Vivek Goyal
2008-07-29 15:15     ` Vivek Goyal
2008-07-29 22:39     ` Simon Horman
2008-07-29 22:39       ` Simon Horman
2008-07-29 22:39       ` Simon Horman
2008-07-29 23:16   ` Simon Horman
2008-07-29 23:16     ` Simon Horman
2008-07-29 23:16     ` Simon Horman
2008-07-29  8:12 ` [patch 3/3] kdump: use is_vmcore_usable() and vmcore_unusable() in reserve_elfcorehdr() Simon Horman
2008-07-29  8:12   ` Simon Horman
2008-07-30 13:01   ` Vivek Goyal
2008-07-30 13:01     ` [patch 3/3] kdump: use is_vmcore_usable() and Vivek Goyal
2008-07-31  0:48     ` [patch 3/3] kdump: use is_vmcore_usable() and vmcore_unusable() in reserve_elfcorehdr() Simon Horman
2008-07-31  0:48       ` Simon Horman
2008-07-31  0:48       ` [patch 3/3] kdump: use is_vmcore_usable() and Simon Horman
2008-07-31 13:21       ` [patch 3/3] kdump: use is_vmcore_usable() and vmcore_unusable() in reserve_elfcorehdr() Vivek Goyal
2008-07-31 13:21         ` Vivek Goyal
2008-07-31 13:21         ` [patch 3/3] kdump: use is_vmcore_usable() and Vivek Goyal
2008-08-01  4:08         ` [patch 3/3] kdump: use is_vmcore_usable() and vmcore_unusable() in reserve_elfcorehdr() Simon Horman
2008-08-01  4:08           ` Simon Horman
2008-08-01  4:08           ` [patch 3/3] kdump: use is_vmcore_usable() and Simon Horman
2008-08-05  7:19           ` [patch 3/3] kdump: use is_vmcore_usable() and vmcore_unusable() in reserve_elfcorehdr() Simon Horman
2008-08-05  7:19             ` Simon Horman
2008-08-05  7:19             ` [patch 3/3] kdump: use is_vmcore_usable() and Simon Horman

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