From: Christoph Hellwig <hch@infradead.org>
To: Halil Pasic <pasic@linux.ibm.com>
Cc: Petr Tesarik <ptesarik@suse.cz>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
linux-s390@vger.kernel.org, Christoph Hellwig <hch@infradead.org>
Subject: Re: Is __dma_direct_alloc_pages broken on s390?
Date: Thu, 18 Jul 2019 06:10:59 -0700 [thread overview]
Message-ID: <20190718131059.GA18742@infradead.org> (raw)
In-Reply-To: <20190718145044.03dc9804.pasic@linux.ibm.com>
On Thu, Jul 18, 2019 at 02:50:44PM +0200, Halil Pasic wrote:
> > I wondered why the kernel works OK on my system, and it is in fact not
> > so bad. If the first allocation fails, the kernel adds GFP_DMA and
> > retries, so this is not fatal, but with a proper definition of
> > ARCH_ZONE_DMA_BITS it should be possible to get success in the first
> > attempt already, let's do it.
> >
> > Petr T
>
> I fully agree! I will post a patch that provides correct
> ARCH_ZONE_DMA_BITS for s390.
>
> BTW I wonder if ARCH_ZONE_DMA_BITS can be inferred from MAX_DMA_ADDRESS,
> and why do we need both.@Christoph, maybe you can help me understand if
> there is a relationship between the two or not, or?
MAX_DMA_ADDRESS is a bit of a weird beast which I honestly do not
understand fully, but most of the uses in common code look a little
bogus, and we should probably get rid of it.
next prev parent reply other threads:[~2019-07-18 13:11 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-18 7:17 Is __dma_direct_alloc_pages broken on s390? Petr Tesarik
2019-07-18 11:36 ` Heiko Carstens
2019-07-18 11:51 ` Petr Tesarik
2019-07-18 12:50 ` Halil Pasic
2019-07-18 13:10 ` Christoph Hellwig [this message]
2019-07-18 14:27 ` Halil Pasic
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