Message-ID: <4D779DE2.5030908@redhat.com>
Date:	Wed, 09 Mar 2011 16:33:54 +0100
From:	Tomas Henzl <thenzl@...hat.com>
To:	scameron@...rdog.cce.hp.com
CC:	james.bottomley@...senpartnership.com, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org, smcameron@...oo.com,
	akpm@...ux-foundation.org, mikem@...rdog.cce.hp.com
Subject: Re: [PATCH 2/2] hpsa: export resettable_on_kexec host attribute

On 03/09/2011 04:14 PM, scameron@...rdog.cce.hp.com wrote:
> On Wed, Mar 09, 2011 at 01:27:53PM +0100, Tomas Henzl wrote:
>   
>> On 03/09/2011 12:10 AM, Stephen M. Cameron wrote:
>>     
>>> From: Stephen M. Cameron <scameron@...rdog.cce.hp.com>
>>>
>>> This attribute, requested by Redhat, allows kexec-tools to know
>>> whether the controller can honor the reset_devices kernel parameter
>>>       
>>     
> [...]
>
>   
>> and actually reset the controller.  For kdump to work properly it
>> Hi Stephen,
>>
>> thanks for posting this.
>> Some of the devices are served by the cciss driver by default - I guess
>> a very similar patch for cciss is needed too.
>> Shouldn't be the 0x409C0E11 and 0x409D0E11 (640x boards) also added to the list?
>> (And the 'unknown' devices.)
>>     
> There's a bit of a fine point here regarding the unknown devices.
>
> If hpsa_allow_any=1 module parameter is set, then the unknown device
> is considered to be resettable (as it's unknown, it's obviously not
> on the list of known unresettable controllers).  If hpsa_allow_any
> is not set, then the unknown devices are not reset -- and the driver
> doesn't even try to do anything with them.  
>
> So, the patch is consistent with this, in that if hpsa_allow_any is
> not set, then there won't be any corresponding sysfs entries at all
> for those devices because those devices won't be service by hpsa
> at all.  And if hpsa_allow_any is set, then those devices will be
> marked as resettable, and the reset code will attempt to reset them.
>
> I think we've got all the unresettable devices listed (when I add the 6400
> boards to the list of course) and I think we're going to try pretty hard to
> make sure new boards are resettable, so, that's probably ok, right?
>   
> Or, do you want to be extra safe, and say that new, unknown boards are assumed
> to be non-resettable?  (Since new boards generally mean driver changes to make
> sure the driver knows those boards, that's not such a big deal -- except for
> people who want to continue to use old OSes on new hardware, which, there seem
> to be quite a few of those people.)
>   
My comment has targeted the new unknown boards, to resolve this it would be easier
to have a list of resettable controllers. (complement to what it is now).

Fact is, that I forgot that a hpsa_allow_any option has to be set before you can
use an 'unknown' controller and combined with your promise 
> we're going to try pretty hard to make sure new boards are resettable
I'm fine with the original approach.

-- tomash


> I think my preference would be to assume that unknown boards are resettable
> if hpsa_allow_any=1, and assume unresettable otherwise (and for purposes of
> sysfs attributes, this is what the patch already does.)
>
> -- steve
>
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