[ofw] Support boot device in IB stack?

Tzachi Dar tzachid at mellanox.co.il
Wed Feb 11 00:55:29 PST 2009

Hi James,

As for 1,3 this are technical changes that can easily be done.

Issue #2 seems much more problematic to me.
First I must say that I haven't studied the topic thoroughly, so I might
be getting a wrong impression of the entire issue.
One more thing to start with, is that I'm not sure that this request is
a must. What I mean by that is that booting will take place just fine.
The one thing that will not work is creating a crash dump file later.

In any case, spinlocks don't really have a problem with higher IRQL (the
way I understand it), but many other commands have. So if the code is
only trying to send/receive data with qps that are open I guess that
things should work. Trying to open new QPs will not work (we have to
wait). Please also note that there are only about 5 commands that can be

Can you please send a reference to the document that says what are the
demands after the system has crashed?

Another question is this, will booting using iSCSI be a better option
for you? (not that it was done using ipoib).


> -----Original Message-----
> From: ofw-bounces at lists.openfabrics.org 
> [mailto:ofw-bounces at lists.openfabrics.org] On Behalf Of James Yang
> Sent: Tuesday, February 10, 2009 11:31 PM
> To: ofw at lists.openfabrics.org
> Subject: [ofw] Support boot device in IB stack?
> Hi,
> We would like to support boot device especially SAN boot over 
> IB. So far I can see the following issues in current code:
> 1) Many functions are page-able. If these functions are 
> running at boot or shut down time, the disk may not be ready, 
> the paging won't work.
> 2) Spinlock may not work for crashdump, whose 
> IRQL>DISPATCH_LEVEL. Any other functions need to be changed 
> 3) All related drivers should be boot start driver.
> Are there any other potential problem? Is there any plan to 
> support SAN boot?
> Please advice.
> Thanks,
> James
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