RE: [Fastboot] [RFC] [PATCH 2/2] kdump: cciss driver initialization issue fix

-----Original Message-----
From: Eric W. Biederman [mailto:ebiederm@xxxxxxxxxxxx]
Sent: Monday, June 26, 2006 12:52 PM
To: Miller, Mike (OS Dev)
Cc: vgoyal@xxxxxxxxxx; Maneesh Soni; Andrew Morton;
Neela.Kolli@xxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx;
fastboot@xxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [Fastboot] [RFC] [PATCH 2/2] kdump: cciss driver
initialization issue fix

"Miller, Mike (OS Dev)" <Mike.Miller@xxxxxx> writes:

Thanks Eric, that helps me understand. Section 8.2.2 of the
open cciss
spec supports a reset message. Target 0x00 is the
controller. We could
add this to the init routine to ensure the board is made sane again
but this would drastically increase init time under normal
circumstances.

Where does the init time penalty come from? How large is the
init penalty? I suspect it is from waiting for the scsi
disks to spin up.
But I am just guessing in the dark.

The penalty is in the firmware and self-test operations.


And I suspect this is a hard reset, also. Not sure if that would
negatively impact kdump. If there were some condition we could test
against and perform the reset when that condition is met it
would not
impact 99.9% of users.

I am wondering if it is possible to look at the controller
and see if it is in a bad state, (i.e. in some state besides
just coming out of reset) and if so issue a reset. If this
really is a long operation that would be the ideal way to handle it.

It's not really in a bad state at this time, is it? Maybe some commands
hanging around.


If the amount of time is really user noticeable and testing
for it is impossible then it is probably time to talk kernel
command line options.

I was informed of the crashboot command line parameter. I can implement
that as a test.


Although it might simply be appropriate to handle commands
completing you didn't start. I am not at all familiar with
that particular piece of hardware so I can't make a good
guess on what needs to happen there.

Not sure about doing this.

mikem
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