linux-kernel - Re: SNB PCI root information

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Message-ID: <20120620193438.GB2248@gmail.com>
Date:	Wed, 20 Jun 2012 21:34:38 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Ulrich Drepper <drepper@...il.com>, jbarnes@...tuousgeek.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	lenb@...nel.org, x86@...nel.org, linux-pci@...r.kernel.org
Subject: Re: SNB PCI root information


* Yinghai Lu <yinghai@...nel.org> wrote:

> On Wed, Jun 20, 2012 at 11:46 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> 
> > As far as I can tell, here's Yinghai's recommendation:  the 
> > user argument should not override BIOS _PXM because if the 
> > BIOS gets the _PXM wrong, the user won't be able to work 
> > around it with the argument, which will force the vendor to 
> > fix the BIOS.
> >
> > I'm not buying it.  The convention that user-supplied 
> > arguments always take precedence is useful, easy to 
> > document, and matches user expectations.  It allows the user 
> > to work around both missing _PXM and incorrect _PXM.
> 
> if the vendor provide _PXM, that _PXM should be right and be 
> trusted.
> 
> if the vendor does not provide _PXM, we can have command line 
> to input it before user can get one updated BIOS from vendor.

So how about an incorrect _PXM, or a slightly inefficient one? 
Why shouldn't it be possible for the user to override it?

I mean, if we create a parameter space that tweaks data then why 
not make it complete and allow *all* firmware data to be 
(optionally) modified, from the kernel boot line?

Thanks,

	Ingo
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