Messages in this thread | | | Subject | Re: [PATCH] arm64: Kconfig: select ZONE_DMA | From | Nicolas Saenz Julienne <> | Date | Thu, 17 Dec 2020 15:53:43 +0100 |
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On Thu, 2020-12-17 at 12:43 +0000, Catalin Marinas wrote: > On Thu, Dec 17, 2020 at 09:44:31AM +0100, Nicolas Saenz Julienne wrote: > > 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 > > Actually, arm64_dma_phys_limit would be zero-initialised. The > ARCH_LOW_ADDRESS_LIMIT becomes ~0UL, hence it covers the whole address > space. > > > > 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 think that's the case, swiotlb is not within the low 32-bit of the > address space. > > > 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) > > Does this limit need to be inclusive?
Yes, I'm missing a '- 1'.
I'll send a fix if there is no further push back/comments.
Regards, Nicolas
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