On Sun, Apr 21, 2013 at 10:31 PM, Takao Indoh <[email protected]> wrote: > (2013/04/20 15:58), Wei Hu wrote: >> On a VT-d capable machine Linux will enable IOMMU by default. If it >> then kexec's a second kernel with intel_iommu=off, this second kernel >> will leave the DMA remapping engine on with no code handling it. The >> symptom is at least USB and SATA drives stop working. This patch fixes >> the problem by always disabling DMA remapping when intel_iommu=off. > > Even when second kernel boots up with intel_iommu=on, dma-remapping need > to be disabled as well before it is initialized and enabled again in > init_dmars(). So, how about something like this? > > for_each_drhd_unit(drhd) { > struct dmar_drhd_unit *drhd; > if (drhd->ignored) > continue; > > iommu = drhd->iommu; > if (iommu->gcmd & DMA_GCMD_TE) > iommu_disable_translation(iommu); > } > > Note, if you agree above code and fix your patch like this, you need > additinal fix to set iommu->gcmd flag sinse gcmd is always zero here. > See first hunk of this patch. > https://lkml.org/lkml/2013/3/20/707
Thanks for your reply. I reviewed your patch. Are you suggesting keeping your change to dmar.c, and moving your change to intel-iommu.c (i.e. the code you just showed) up after the call to dmar_table_init()? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
