On 01/08/2018 07:28 AM, Yves-Alexis Perez wrote:

On Mon, 2018-01-08 at 15:19 +0000, Ben Hutchings wrote:

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I tried this on a ThinkPad X230 (Ivy Bridge CPU, i7 3520M, so pcid but not invpcid) on full UEFI mode and it doesn't boot at all. grub-efi loads the kernel and initrd, but I don't have any message after “Loading initial ramdisk” (even with debug earlyprintk=vga).

If you boot with EFI you need to use earlyprintk=efi.

Thanks! With that, I can see the last few log lines before it hangs:

Kernel/User page tables isolation: enabled […] bootconsole [earlyefi0] disabled

Does "earlyprintk=efi,keep" help get more out to the console?

Also I must have done something wrong earlier today, because when booting with 'nopcid' it does work (which is consistent with other people tests, afaict).

If I had to guess, I'd say we're probably putting a PCID value into the low bits of CR3 before we've _enabled_ PCID support in the CPU.