On Thu, Jul 25, 2019 at 02:42:22PM -0700, Matthew Wilcox wrote: > On Thu, Jul 25, 2019 at 10:38:58PM +0100, Russell King - ARM Linux admin wrote: > > On Thu, Jul 25, 2019 at 07:39:21AM -0700, Matthew Wilcox wrote: > > > But 'page' isn't necessarily PMD-aligned. I don't think we can rely on > > > architectures doing the right thing if asked to make a PMD for a randomly > > > aligned page. > > > > > > How about finding the physical address of something like kernel_init(), > > > and using the corresponding pte/pmd/pud/p4d/pgd that encompasses that > > > address? It's also better to pass in the pfn/page rather than using global > > > variables to communicate to the test functions. > > > > There are architectures (32-bit ARM) where the kernel is mapped using > > section mappings, and we don't expect the Linux page table walking to > > work for section mappings. > > This test doesn't go so far as to insert the PTE/PMD/PUD/... into the > page tables. It merely needs an appropriately aligned PFN to create a > PTE/PMD/PUD/... from. Well, in any case, c085ac68 t kernel_init so I'm not sure that would be an improvement. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
