From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>,
Jonathan Corbet <corbet@lwn.net>,
Magnus Damm <magnus.damm@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
iommu@lists.linux-foundation.org,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH 2/2] swiotlb: Add swiotlb=nobounce debug option
Date: Mon, 7 Nov 2016 14:20:12 -0500 [thread overview]
Message-ID: <20161107192012.GB4750@char.us.oracle.com> (raw)
In-Reply-To: <CAMuHMdXFCVP2L-1jdzxbA6JD2Pm4accCyc57fFXt=g7VgAv53Q@mail.gmail.com>
On Mon, Nov 07, 2016 at 07:57:11PM +0100, Geert Uytterhoeven wrote:
> Hi Konrad,
>
> On Mon, Oct 31, 2016 at 6:52 PM, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
> > On Mon, Oct 31, 2016 at 04:45:04PM +0100, Geert Uytterhoeven wrote:
> >> On architectures like arm64, swiotlb is tied intimately to the core
> >> architecture DMA support. In addition, ZONE_DMA cannot be disabled.
> >>
> >> To aid debugging and catch devices not supporting DMA to memory outside
> >> the 32-bit address space, add a kernel command line option
> >> "swiotlb=nobounce", which disables the use of bounce buffers.
> >> If specified, trying to map memory that cannot be used with DMA will
> >> fail, and a warning will be printed (rate-limited).
> >
> > I would make the 'swiotlb_force' an enum. And then instead of this
> > being 'nobounce' just do the inverse of 'force', that is the
> > 'noforce' would trigger this no bounce effect.
> >
> > So:
> >
> > enum {
> > NORMAL, /* Default - depending on the hardware DMA mask and such. */
> > FORCE, /* swiotlb=force */
> > NO_FORCE, /* swiotlb=noforce */
>
> Fine for me, but swiotlb_force is exported to platform code. Hence all users
> should be updated?
Yeah it would have to be moved to the swiotlb.h (the enum).
Thanks!
prev parent reply other threads:[~2016-11-07 19:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-31 15:45 [PATCH 0/2] swiotlb: Rate-limit printing and 64-bit memory debugging Geert Uytterhoeven
2016-10-31 15:45 ` [PATCH 1/2] swiotlb: Rate-limit printing when running out of SW-IOMMU space Geert Uytterhoeven
2016-10-31 16:02 ` Sergei Shtylyov
2016-11-05 19:40 ` Konrad Rzeszutek Wilk
2016-10-31 15:45 ` [PATCH 2/2] swiotlb: Add swiotlb=nobounce debug option Geert Uytterhoeven
2016-10-31 17:41 ` Robin Murphy
2016-10-31 18:20 ` Geert Uytterhoeven
2016-11-01 11:46 ` Robin Murphy
2016-11-07 15:41 ` Geert Uytterhoeven
2016-11-07 17:18 ` Robin Murphy
2016-10-31 17:52 ` Konrad Rzeszutek Wilk
2016-11-07 18:57 ` Geert Uytterhoeven
2016-11-07 19:20 ` Konrad Rzeszutek Wilk [this message]
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