Re: [PATCH] swiotlb: swiotlb_{alloc,free}_buffer should depend on CONFIG_DMA_DIRECT_OPS

From: Konrad Rzeszutek Wilk
Date: Sun Mar 25 2018 - 01:38:33 EST


On Sat, Mar 24, 2018 at 06:03:51PM +0100, Christoph Hellwig wrote:
> On Fri, Mar 23, 2018 at 02:57:07PM -0400, Konrad Rzeszutek Wilk wrote:
> > On Fri, Mar 23, 2018 at 06:49:30PM +0100, Christoph Hellwig wrote:
> > > Otherwise we might get unused symbol warnings for configs that built
> > > swiotlb.c only for use by xen-swiotlb.c and that don't otherwise select
> > > CONFIG_DMA_DIRECT_OPS, which is possible on arm.
> > >
> > > Fixes: 16e73adbca76 ("dma/swiotlb: Remove swiotlb_{alloc,free}_coherent()")
> > > Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> > > Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> >
> >
> > Alternatively could we set the Kconfig to slect DMA_DIRECT_OPS?
>
>
> IFF we build swiotlb.c only for xen-swiotlb we don't need DMA_DIRECT_OPS.

I don't think there is ever an case where you want a Xen specific build.

> IF you are fine with just requring it as well that would be doable nicely
> only if we consolidate to a single defintion of CONFIG_SWIOTLB instead
> of one per architecture. Which is something we should do anyway,
> so I'll look into it once I get some time.

Sounds good. Thank you.