Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [RFC PATCH 0/3] generic hypercall support | Date | Fri, 8 May 2009 00:11:52 +0200 |
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On Thursday 07 May 2009, Chris Wright wrote: > > > Chris, is that issue with the non ioread/iowrite access of a mangled > > pointer still an issue here? I would think so, but I am a bit fuzzy on > > whether there is still an issue of non-wrapped MMIO ever occuring. > > Arnd was saying it's a bug for other reasons, so perhaps it would work > out fine.
Well, maybe. I only said that __raw_writel and pointer dereference is bad, but not writel.
IIRC when we had that discussion about io-workarounds on powerpc, the outcome was that passing an IORESOURCE_MEM resource into pci_iomap must still result in something that can be passed into writel in addition to iowrite32, while an IORESOURCE_IO resource may or may not be valid for writel and/or outl.
Unfortunately, this means that either readl/writel needs to be adapted in some way (e.g. the address also ioremapped to the mangled pointer) or the mechanism will be limited to I/O space accesses.
Maybe BenH remembers the details better than me.
Arnd <>< -- 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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