On 04/24/15 at 04:35pm, Baoquan He wrote: > On 04/24/15 at 04:25pm, Dave Young wrote: > > Hi, Baoquan > > > > > I support this patchset. > > > > > > We should not fear oldmem since reserved crashkernel region is similar. > > > No one can guarantee that any crazy code won't step into crashkernel > > > region just because 1st kernel says it's reversed for kdump kernel. Here > > > the root table and context tables are also not built to allow legal code > > > to danamge. Both of them has the risk to be corrupted, for trying our > > > best to get a dumped vmcore the risk is worth being taken. > > > > old mem is mapped in 1st kernel so compare with the reserved crashkernel > > they are more likely to be corrupted. they are totally different. > > Could you tell how and why they are different? Wrong code will choose > root tables and context tables to danamge when they totally lose > control? iommu will map io address to system ram, right? not to reserved ram, but yes I'm assuming the page table is right, but I was worrying they are corrupted while kernel panic is happening. > > > > > > > > > And the resetting pci way has been NACKed by David Woodhouse, the > > > maintainer of intel iommu. Because the place calling the resetting pci > > > code is ugly before kdump kernel or in kdump kernel. And as he said a > > > certain device made mistakes why we blame on all devices. We should fix > > > that device who made mistakes. > > > > Resetting pci bus is not ugly than fixing a problem with risk and to fix > > the problem it introduced in the future. > > There's a problem, we fix the problem. If that's uglier, I need redefine > the 'ugly' in my personal dict. You mean the problem it could introduce > is wrong code will damage root table and context tables, why don't we > fix that wrong code, but blame innocent context tables? So you mean > these tables should deserve being damaged by wrong code? I'm more than happy to see this issue can be fixed in the patchset, I do not agree to add the code there with such problems. OTOH, for now seems there's no way to fix it. > > > > > I know it is late to speak out, but sorry I still object and have to NACK this > > oldmem approach from my point. > > > > Thanks > > Dave -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
