Messages in this thread | | | Date | Tue, 24 Nov 2009 18:35:12 +0900 | Subject | Re: [PATCH] x86: fix gart iommu using for amd 64 bit system | From | FUJITA Tomonori <> |
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On Tue, 24 Nov 2009 01:19:21 -0800 Yinghai Lu <yinghai@kernel.org> wrote:
> FUJITA Tomonori wrote: > > On Sat, 21 Nov 2009 20:24:52 -0800 > > Yinghai Lu <yinghai@kernel.org> wrote: > > > >> amd 64 systems that > >> 1. do not have AGP > >> 2. do not have IOMMU > >> 3. mem > 4g > >> 4. BIOS do not allocate correct gart in NB. > >> will leave them to use SWIOTLB forcely. > > > > Sorry, I forgot about this GART workaround. > > > > > >> Index: linux-2.6/arch/x86/kernel/pci-dma.c > >> =================================================================== > >> --- linux-2.6.orig/arch/x86/kernel/pci-dma.c > >> +++ linux-2.6/arch/x86/kernel/pci-dma.c > >> @@ -124,11 +124,12 @@ void __init pci_iommu_alloc(void) > >> /* free the range so iommu could get some range less than 4G */ > >> dma32_free_bootmem(); > >> #endif > >> + if (!swiotlb_force) > >> + gart_iommu_hole_init(); > >> + > >> if (pci_swiotlb_init()) > >> return; > >> > >> - gart_iommu_hole_init(); > >> - > >> detect_calgary(); > >> > >> detect_intel_iommu(); > > > > I prefer to detect all the IOMMU drivers in a consistent way; > > detecting only GART before swioltb doesn't look nice. > > > > As we did before, we could detect all the IOMMU driver before > > swiotlb. However, I think that it's better to simply change > > pci_swiotlb_init() not to steal the preallocate GART workaround memory. > > > > btw, initializing swiotlb before IOMMU detection is useful to GART > > too? If GART can't allocate the workaround memory, then the kernel > > panic now. We can use swiotlb instead in that case? > > > > = > > From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> > > Subject: [PATCH] x86: stop swiotlb stealing the GART workaround memory > > > > swiotlb wrongly uses the GART workaround memory (for bad BIOS) that > > dma32_reserv_bootmem allocates. We need to initialize swiotlb before > > dma32_free_bootmem(). > > > > Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> > > --- > > arch/x86/kernel/pci-dma.c | 6 +++++- > > 1 files changed, 5 insertions(+), 1 deletions(-) > > > > diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c > > index afcc58b..26fe2cd 100644 > > --- a/arch/x86/kernel/pci-dma.c > > +++ b/arch/x86/kernel/pci-dma.c > > @@ -120,11 +120,15 @@ static void __init dma32_free_bootmem(void) > > > > void __init pci_iommu_alloc(void) > > { > > + int use_swiotlb; > > + > > + use_swiotlb = pci_swiotlb_init(); > > + > > #ifdef CONFIG_X86_64 > > /* free the range so iommu could get some range less than 4G */ > > dma32_free_bootmem(); > > #endif > > - if (pci_swiotlb_init()) > > + if (use_swiotlb) > > return; > > > > gart_iommu_hole_init(); > > pci_swiotlb_init need be called after dma32_free_bootmem > otherwise it could fail for system with lots of memory and numa=off
Why? swiotlb needs just 64MB (and some) in DMA32.
swiotlb had been worked fine without that hack until 2.6.26?
Only broken GART needs that hack (and I think that it's better to move that hack to GART code).
> so dma32_free_bootmem will work for gart_iommu_hole_init and pci_swiotlb_init.. > make sure they can get RAM < 4g. > > also in gart_iommu_hole_init we need check swiotlb and !valid_agp... > - } else if (!valid_agp) { > + } else if (swiotlb && !valid_agp) { > > otherwise the the workaround will be skipped... > > YH > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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