linux-kernel - Re: USB storage no-boot regression (bisected)

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Date:	Wed, 15 Apr 2009 13:06:14 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	VomLehn <dvomlehn@...co.com>, Mark Lord <lkml@....ca>,
	Alan Stern <stern@...land.harvard.edu>,
	Greg KH <greg@...ah.com>, Jeff Garzik <jeff@...zik.org>,
	Linux USB kernel mailing list <linux-usb@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: USB storage no-boot regression (bisected)

On Wed, 15 Apr 2009 18:32:52 +0100
Alan Cox <alan@...rguk.ukuu.org.uk> wrote:

> > Saying that we were "lucky" that things worked before is no help and
> > you should be aware that it ticks people off. 
> 
> No doubt those who wrote the code and never expected that timing to
> reliably work will take affront at those who blame them for it not
> working. 

It's even more than that; it's OTHER code that gets faster that
can/will break this.

> Those who expected it to work and never knew it was not
> guaranteed will feel likewise in reverse.

For storage at least the solution already existed (root_wait);
it just hasn't been used consistently.

For other pieces it's hard. Non-enumeratable busses just suck;
at some point all you can do is just wait (which we have already 
available today for anyone to do). I realize people don't want to
just wait 4 seconds (the people who first objected to boot time
improvements then suddenly care about boot time ;-)...

For root fs there's some options, and I have patches to basically retry
on fail. (The patches have a bug and I don't have time to solve it this
week, so I'm not submitting them)
For other devices it is hard. Realistically we need hotplug to work
well enough so that when a device shows up, we can just hook it up when
it does.

-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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