Re: [PATCH] IB/ipath: use arch_phys_wc_add() and require PAT disabled

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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On Mon, 2015-04-27 at 09:46 -0700, Luis R. Rodriguez wrote:
> On Wed, Apr 22, 2015 at 12:26 PM, Luis R. Rodriguez
> <mcgrof-3uybbJdB1yH774rrrx3eTA@public.gmane.org> wrote:
> > From: "Luis R. Rodriguez" <mcgrof-IBi9RG/b67k@public.gmane.org>
> >
> > We are burrying direct access to MTRR code support on
> > x86 in order to take advantage of PAT. In the future we
> > also want to make the default behaviour of ioremap_nocache()
> > to use strong UC, use of mtrr_add() on those systems
> > would make write-combining void.
> >
> > In order to help both enable us to later make strong
> > UC default and in order to phase out direct MTRR access
> > code port the driver over to arch_phys_wc_add() and
> > annotate that the device driver requires systems to
> > boot with PAT disabled, with the nopat kernel parameter.
> >
> > This is a worthy compromise given that the ipath device
> > driver powers the old HTX bus cards that only work in
> > AMD systems, while the newer IB/qib device driver
> > powers all PCI-e cards. The ipath device driver is
> > obsolete, hardware hard to find and because of this
> > this its a reasonable compromise to make to require
> > users of ipath to boot with nopat.
> 
> Hey folks, I realize its being discussed whether or not to remove the
> driver entirely from the kernel but in the meantime, is this a
> reasonable compromise ?

[ trimmed Cc: list to probably the only people that care ]

I would think so.  I think we might as well mark this driver as
deprecated and put a tentative date on removal while we are at it.

Mike, any specific input here?  I would suggest mark it deprecated with
a planned removal sometime in late 2015/early 2016.

-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
              GPG KeyID: 0E572FDD



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