On Wed, Nov 29, 2017 at 05:40:32PM +0100, Thomas Gleixner wrote: > On Wed, 29 Nov 2017, Kirill A. Shutemov wrote: > > > On Wed, Nov 29, 2017 at 04:49:08PM +0100, Borislav Petkov wrote: > > > On Sat, Nov 11, 2017 at 01:06:41AM +0300, Kirill A. Shutemov wrote: > > > > Hi Ingo, > > > > > > > > Here's updated changes that prepare the code to boot-time switching between > > > > paging modes and handle booting in 5-level mode when bootloader put kernel > > > > image above 4G, but haven't enabled 5-level paging for us. > > > > > > Btw, if I enable CONFIG_X86_5LEVEL with 4.15-rc1 on an AMD box, the box > > > triple-faults and ends up spinning in a reboot loop. Even though it > > > should say: > > > > > > early console in setup code > > > This kernel requires the following features not present on the CPU: > > > la57 > > > Unable to boot - please use a kernel appropriate for your CPU. > > > > > > and halt. > > > > > > A kvm guest still does that but baremetal triple-faults. > > > > > > Ideas? > > > > Looks like we call check_cpuflags() too late. 5-level paging gets enabled > > before image decompression started. > > > > For qemu/kvm it works because it's supported in softmmu, even if not > > advertised in cpuid. > > > > I'm not sure if it worth fixing on its own. I would rather get boot-time > > switching code upstream sooner. It will get problem go away naturally. > > It needs to be fixed now. Because that problem exists in 4.14 Okay. We're really early in the boot -- startup_64 in decompression code -- and I don't know a way print a message there. Is there a way? no_longmode handled by just hanging the machine. Is it enough for no_la57 case too? -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
