From: Artem Bityutskiy <dedekind1@gmail.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Hong XU <hong.xu@atmel.com>,
Nicolas Ferre <nicolas.ferre@atmel.com>,
Patrice VILCHEZ <patrice.vilchez@atmel.com>,
Linux Kernel list <linux-kernel@vger.kernel.org>,
linux-mtd <linux-mtd@lists.infradead.org>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
Andrew Victor <linux@maxim.org.za>,
"'linux-arm-kernel@lists.infradead.org'"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: Hit BUG_ON in dma-mapping.c:425 (RFC)
Date: Thu, 24 Mar 2011 13:08:07 +0200 [thread overview]
Message-ID: <1300964887.2735.84.camel@localhost> (raw)
In-Reply-To: <20110324092732.GA19935@n2100.arm.linux.org.uk>
On Thu, 2011-03-24 at 09:27 +0000, Russell King - ARM Linux wrote:
> The only real answer I can give is: if you want to deal with DMA, you
> absolutely must conform to the restrictions on DMA which means that you
> can't pass vmalloc addresses to the DMA API.
I see, thanks. Well, I do not see any issues with changing MTD-related
SW (JFFS2, UBI, UBIFS, etc) to use kmalloc. But this would require som
non-trivial efforts, although I believe this is doable.
Basically, we have to work with entire eraseblocks often, which may be
128KiB or 256KiB or even 512KiB nowadays. And we vmalloc the
eraseblock-sized buffers in these cases.
We could instead work with arrays of pages (or multiple pages), and then
do things like readv/writev. But this requires a brave knight who'd come
and just implemented this, or a company who'd fund someone to work on
this.
--
Best Regards,
Artem Bityutskiy (Артём Битюцкий)
WARNING: multiple messages have this Message-ID (diff)
From: dedekind1@gmail.com (Artem Bityutskiy)
To: linux-arm-kernel@lists.infradead.org
Subject: Hit BUG_ON in dma-mapping.c:425 (RFC)
Date: Thu, 24 Mar 2011 13:08:07 +0200 [thread overview]
Message-ID: <1300964887.2735.84.camel@localhost> (raw)
In-Reply-To: <20110324092732.GA19935@n2100.arm.linux.org.uk>
On Thu, 2011-03-24 at 09:27 +0000, Russell King - ARM Linux wrote:
> The only real answer I can give is: if you want to deal with DMA, you
> absolutely must conform to the restrictions on DMA which means that you
> can't pass vmalloc addresses to the DMA API.
I see, thanks. Well, I do not see any issues with changing MTD-related
SW (JFFS2, UBI, UBIFS, etc) to use kmalloc. But this would require som
non-trivial efforts, although I believe this is doable.
Basically, we have to work with entire eraseblocks often, which may be
128KiB or 256KiB or even 512KiB nowadays. And we vmalloc the
eraseblock-sized buffers in these cases.
We could instead work with arrays of pages (or multiple pages), and then
do things like readv/writev. But this requires a brave knight who'd come
and just implemented this, or a company who'd fund someone to work on
this.
--
Best Regards,
Artem Bityutskiy (????? ????????)
WARNING: multiple messages have this Message-ID (diff)
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>,
"'linux-arm-kernel@lists.infradead.org'"
<linux-arm-kernel@lists.infradead.org>,
Linux Kernel list <linux-kernel@vger.kernel.org>,
Patrice VILCHEZ <patrice.vilchez@atmel.com>,
Hong XU <hong.xu@atmel.com>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
Andrew Victor <linux@maxim.org.za>,
linux-mtd <linux-mtd@lists.infradead.org>
Subject: Re: Hit BUG_ON in dma-mapping.c:425 (RFC)
Date: Thu, 24 Mar 2011 13:08:07 +0200 [thread overview]
Message-ID: <1300964887.2735.84.camel@localhost> (raw)
In-Reply-To: <20110324092732.GA19935@n2100.arm.linux.org.uk>
On Thu, 2011-03-24 at 09:27 +0000, Russell King - ARM Linux wrote:
> The only real answer I can give is: if you want to deal with DMA, you
> absolutely must conform to the restrictions on DMA which means that you
> can't pass vmalloc addresses to the DMA API.
I see, thanks. Well, I do not see any issues with changing MTD-related
SW (JFFS2, UBI, UBIFS, etc) to use kmalloc. But this would require som
non-trivial efforts, although I believe this is doable.
Basically, we have to work with entire eraseblocks often, which may be
128KiB or 256KiB or even 512KiB nowadays. And we vmalloc the
eraseblock-sized buffers in these cases.
We could instead work with arrays of pages (or multiple pages), and then
do things like readv/writev. But this requires a brave knight who'd come
and just implemented this, or a company who'd fund someone to work on
this.
--
Best Regards,
Artem Bityutskiy (Артём Битюцкий)
next prev parent reply other threads:[~2011-03-24 11:08 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-05 16:49 Hit BUG_ON in dma-mapping.c:425 Nicolas Ferre
2011-01-05 16:49 ` Nicolas Ferre
2011-01-05 16:55 ` Russell King - ARM Linux
2011-01-05 16:55 ` Russell King - ARM Linux
2011-01-06 10:38 ` Nicolas Ferre
2011-01-06 10:38 ` Nicolas Ferre
2011-01-06 10:38 ` Nicolas Ferre
2011-01-06 11:19 ` Artem Bityutskiy
2011-01-06 11:19 ` Artem Bityutskiy
2011-01-06 11:19 ` Artem Bityutskiy
2011-03-24 8:18 ` Hit BUG_ON in dma-mapping.c:425 (RFC) Nicolas Ferre
2011-03-24 8:18 ` Nicolas Ferre
2011-03-24 8:18 ` Nicolas Ferre
2011-03-24 8:25 ` Russell King - ARM Linux
2011-03-24 8:25 ` Russell King - ARM Linux
2011-03-24 8:25 ` Russell King - ARM Linux
2011-03-24 8:36 ` Artem Bityutskiy
2011-03-24 8:36 ` Artem Bityutskiy
2011-03-24 8:36 ` Artem Bityutskiy
2011-03-24 9:27 ` Russell King - ARM Linux
2011-03-24 9:27 ` Russell King - ARM Linux
2011-03-24 9:27 ` Russell King - ARM Linux
2011-03-24 9:41 ` Russell King - ARM Linux
2011-03-24 9:41 ` Russell King - ARM Linux
2011-03-24 11:08 ` Artem Bityutskiy [this message]
2011-03-24 11:08 ` Artem Bityutskiy
2011-03-24 11:08 ` Artem Bityutskiy
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