|Summary:||12-BETA PAE kernel does not boot|
|Component:||kern||Assignee:||freebsd-bugs mailing list <bugs>|
|Severity:||Affects Only Me||CC:||kib|
Description ota 2018-12-06 03:08:39 UTC
12-BETA, releng/12.0 PAE, kernel fails to boot and restarts the hardware. I built with make buildkernel KERNCONF=PAE. After loader starts booting kernel, it is nearly instantly restarts the hardware so that I couldn't get any more useful information. I tested on VMWare and 1 hardware that both boots 11.2-RELEASE and 11.3-STABLE PAE. I plan to get a revision # when PAE started failing but I need some time to figure out.
Comment 1 Konstantin Belousov 2018-12-08 03:11:30 UTC
Created attachment 199945 [details] Ignore nx for kernel_pmap I might make the patch more fine-grained later.
Comment 2 ota 2018-12-08 04:01:18 UTC
(In reply to Konstantin Belousov from comment #1) This change allowed PAE kernel to boot. Thank you for quick response.
Comment 3 commit-hook 2018-12-08 22:13:04 UTC
A commit references this bug: Author: kib Date: Sat Dec 8 22:12:58 UTC 2018 New revision: 341746 URL: https://svnweb.freebsd.org/changeset/base/341746 Log: Fix PAE boot. With the introduction of M_EXEC support for kmem_malloc(), some kernel mappings start having NX bit set in the paging structures early, for PAE kernels on machines with NX support, i.e. practically on all machines. In particular, AP trampoline and initialization needs to access pages which translations has NX bit set, before initializecpu() is called. Check for CPUID NX feature and enable EFER.NXE before we enable paging in mp boot trampoline. This allows the CPU to use the kernel page table instead of generating page fault due to reserved bit set. PR: 233819 Sponsored by: The FreeBSD Foundation MFC after: 1 week Changes: head/sys/i386/i386/mpboot.s