From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Stefan Wahren <stefan.wahren@i2se.com>,
Robin Murphy <robin.murphy@arm.com>,
Florian Fainelli <f.fainelli@gmail.com>,
Maxime Ripard <maxime@cerno.tech>, Christoph Hellwig <hch@lst.de>,
Phil Elwell <phil@raspberrypi.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Alexander Stein <alexander.stein@ew.tq-group.com>
Subject: Re: ARM_LPAE + VMSPLIT_2G cause swiotlb warning on Raspberry Pi 4
Date: Wed, 17 May 2023 12:06:35 +0100 [thread overview]
Message-ID: <ZGS1OyZx4JQTLxlz@shell.armlinux.org.uk> (raw)
In-Reply-To: <5cda1c4b-4c32-4509-9b02-62b2c6b50827@app.fastmail.com>
On Wed, May 17, 2023 at 12:54:30PM +0200, Arnd Bergmann wrote:
> On Wed, May 17, 2023, at 12:34, Arnd Bergmann wrote:
> > On Wed, May 17, 2023, at 12:24, Stefan Wahren wrote:
> >> Am 17.05.23 um 12:06 schrieb Robin Murphy:
> >>> On 2023-05-17 07:23, Stefan Wahren wrote:
> >
> > I think LPAE doesn't affect it, the configurations that Stefan
> > mentioned were LPAE with VMSPLIT_2G (broken), non-LPAE with
> > VMSPLIT_3G (works) and LPAE with VMSPLIT_3G (works). I would assume
> > that non-LPAE with VMSPLIT_2G or VMSPLIT_3G_OPT is also broken.
> >
> >> This one?
> >> [ 0.000000] software IO TLB: area num 4.
> >> [ 0.000000] software IO TLB: mapped [mem
> >> 0x0000000069e7f000-0x000000006de7f000] (64MB)
> >
> > Indeed, that is clearly above the .dma_zone_size value from
> > the machine descriptor.
>
> It looks like Arm does not set the ARCH_LOW_ADDRESS_LIMIT
> constant for swiotlb, so it gets the default 4GB maximum.
>
> I think this would work on arm, though it's probably not the
> correct fix in general, as I think MAX_DMA_ADDRESS is meant
> to refer to the ISA_DMA_API limit, not the ZONE_DMA limit.:
MAX_DMA_ADDRESS is a _virtual_ address. What is ARCH_LOW_ADDRESS_LIMIT?
I can find no reference to this in obvious places (mm/ lib/ kernel/
drivers/base/ drivers/iommu/)
--
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next prev parent reply other threads:[~2023-05-17 11:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-16 20:46 ARM_LPAE + VMSPLIT_2G cause swiotlb warning on Raspberry Pi 4 Stefan Wahren
2023-05-16 22:17 ` Florian Fainelli
2023-05-17 6:23 ` Stefan Wahren
2023-05-17 10:06 ` Robin Murphy
2023-05-17 10:24 ` Stefan Wahren
2023-05-17 10:34 ` Arnd Bergmann
2023-05-17 10:54 ` Arnd Bergmann
2023-05-17 11:06 ` Russell King (Oracle) [this message]
2023-05-17 11:08 ` Russell King (Oracle)
2023-05-17 11:08 ` Robin Murphy
2023-05-17 14:35 ` Stefan Wahren
2023-05-17 14:45 ` Russell King (Oracle)
2023-05-17 17:40 ` Stefan Wahren
2023-05-17 10:36 ` Robin Murphy
2023-05-17 7:37 ` Arnd Bergmann
2023-05-17 10:40 ` Stefan Wahren
2023-05-17 11:00 ` Arnd Bergmann
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