Messages in this thread | | | Subject | Re: [PATCH] arm64: Kconfig: select ZONE_DMA | From | Nicolas Saenz Julienne <> | Date | Thu, 17 Dec 2020 09:44:31 +0100 |
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Hi Peng, sorry for the inconvenience, this is most probably related to these changes: https://lore.kernel.org/linux-arm-kernel/20201119175400.9995-1-nsaenzjulienne@suse.de/
On Thu, 2020-12-17 at 16:08 +0800, Peng Fan (OSS) wrote: > From: Peng Fan <peng.fan@nxp.com> > > ZONE_DMA should not be disabled, otherwise arm64_dma_phys_limit is > left uninitialized and cause swiotlb have IO TLB above 4GB which > might crash some platforms > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > --- > > Not sure whether need to address code to initialize the variables or > force select ZONE_DMA
What is the cause for the swiotlb related crashes? I assume it's DMA into an address too high for the bus, but it might be something else.
I figure you have a setup with ZONE_DMA32, ZONE_NORMAL and !ZONE_DMA.
First of all, I'd suggest you try arm64's defaults (all zones enabled), the series I mention above should fix most of the issues we've had with ZONE_DMA/ZONE_DMA32 in the past. We now parse DT/ACPI and only create two distinct DMA zones if really needed. Otherwise ZONE_DMA spans the whole 32 bit address space.
That said, IMO we're not doing the right thing in the !ZONE_DMA && ZONE_DMA32 case, and this should fix it (I didn't test it):
- #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit - 1) + #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit ? : arm64_dma32_phys_limit)
Regards, Nicolas
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