Messages in this thread | | | Subject | Re: X86_64 + VIA + 4g problems | From | Andi Kleen <> | Date | 03 Jan 2006 22:26:06 +0100 |
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Dieter Stüken <stueken@conterra.de> writes: [can you please not always drop me from cc with each reply?]
Dieter Stüken <stueken@conterra.de> writes:
> OK, here are my last results for today: > > using "iommu=allowed" did not work. System freezes during initialization > of the PDC20318, which is on the external PCI bus. > > But swiotlb=force works well!
This means your PCI bridge doesn't support addresses >4GB.
> The pci-gart.c patch seems to disable dma.
Only DMA for addresses >4GB.
> Is this the DMA my PCI devices > perform them self? As I learned, they may perform DMA even above 4g if all > works well. Thus I may be happy without any IOMMU. As I saw my system working > even without this patch, I will turn back to the original 2.6.15-rc7 an continue > running this torture test during this night.
The patch should perform slightly better than swiotlb=force because it will only force bounce buffering for addresses >4GB.
If your torture test involves more than 64MB of IO in flight you might also need to increase the bounce buffer area with swiotlb=128M or somesuch.
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