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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>,
	linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
	Christian Zigotzky <chzigotzky@xenosoft.de>,
	linuxppc-dev@lists.ozlabs.org,
	Larry Finger <Larry.Finger@lwfinger.net>
Subject: Re: [BISECTED REGRESSION] b43legacy broken on G4 PowerBook
Date: Tue, 11 Jun 2019 16:58:12 +1000	[thread overview]
Message-ID: <fdfc817d1dcdc83f5bc45f0ab12cbce0c61e6702.camel@kernel.crashing.org> (raw)
In-Reply-To: <20190611060816.GA20158@lst.de>

On Tue, 2019-06-11 at 08:08 +0200, Christoph Hellwig wrote:
> On Tue, Jun 11, 2019 at 03:56:33PM +1000, Benjamin Herrenschmidt
> wrote:
> > The reason I think it sort-of-mostly-worked is that to get more
> > than
> > 1GB of RAM, those machines use CONFIG_HIGHMEM. And *most* network
> > buffers aren't allocated in Highmem.... so you got lucky.
> > 
> > That said, there is such as thing as no-copy send on network, so I
> > wouldn't be surprised if some things would still have failed, just
> > not
> > frequent enough for you to notice.
> 
> Unless NETIF_F_HIGHDMA is set on a netdev, the core networkign code
> will bounce buffer highmem pages for the driver under all
> circumstances.

 ... which b43legacy doesn't set to the best of my knowledge ...

Which makes me wonder how come it didn't work even with your patches ?
AFAIK, we have less than 1GB of lowmem unless the config has been
tweaked....

Cheers,
Ben.



  reply	other threads:[~2019-06-11  7:06 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-05 22:50 [BISECTED REGRESSION] b43legacy broken on G4 PowerBook Aaro Koskinen
2019-06-06  0:54 ` Benjamin Herrenschmidt
2019-06-06  9:31   ` Aaro Koskinen
2019-06-06 10:56     ` Benjamin Herrenschmidt
2019-06-06 10:57       ` Benjamin Herrenschmidt
2019-06-06 11:43         ` Christoph Hellwig
2019-06-06 19:26           ` Larry Finger
2019-06-06 20:11           ` Larry Finger
2019-06-06  3:06 ` Larry Finger
2019-06-06  6:40   ` Christoph Hellwig
2019-06-07 17:25 ` Larry Finger
2019-06-07 17:29   ` Christoph Hellwig
2019-06-07 18:50     ` Larry Finger
2019-06-08 21:52     ` Larry Finger
2019-06-10  8:18       ` Christoph Hellwig
2019-06-10 16:09         ` Larry Finger
2019-06-11  6:05           ` Christoph Hellwig
2019-06-11 22:20             ` Larry Finger
2019-06-11 22:46               ` Aaro Koskinen
2019-06-12  1:57                 ` Larry Finger
2019-06-11 22:46               ` Benjamin Herrenschmidt
2019-06-12  1:52                 ` Larry Finger
2019-06-12  3:32                   ` Benjamin Herrenschmidt
2019-06-12  6:55               ` Christoph Hellwig
2019-06-12 19:41                 ` Larry Finger
2019-06-12 21:59                   ` Benjamin Herrenschmidt
2019-06-13  7:29                     ` Christoph Hellwig
2019-06-11 17:48           ` Andreas Schwab
2019-06-08  4:21   ` Benjamin Herrenschmidt
2019-06-08  7:23     ` Christoph Hellwig
2019-06-10 18:44     ` Larry Finger
2019-06-11  5:56       ` Benjamin Herrenschmidt
2019-06-11  6:08         ` Christoph Hellwig
2019-06-11  6:58           ` Benjamin Herrenschmidt [this message]
2019-06-11  6:59             ` Benjamin Herrenschmidt
2019-06-11  7:54               ` Christoph Hellwig
2019-06-11  9:04                 ` Benjamin Herrenschmidt
2019-06-11  7:53             ` Christoph Hellwig

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