On 12 November 2014 15:59, Emmanuel Dreyfus <manu%netbsd.org@localhost>
An i386 domU kernel will crash on startup of LOCKDEBUG kernel option is
enabled and vcpu is more than 1.
The backtrace is below. Finding the offending code is easy, and I
understand that LOCKDEBUG globals are not initialized at the time this
mutex is used. I am not sure of the proper fix, though.
Does the following patch work for you ?
It's a bit tricky since we use uvm_km_alloc() at early bootup (even for ci, I think this should come from a static array or a poolcache) which is what triggers the pmap_growkernel() as you probably know.
The mutex needs to be init()ed as early as possible, which is my intention with this change.
diff -r bed6f574351e sys/arch/xen/x86/cpu.c
--- a/sys/arch/xen/x86/cpu.c Sun Sep 07 00:15:54 2014 +0530
+++ b/sys/arch/xen/x86/cpu.c Tue Nov 18 10:09:02 2014 +0530
@@ -397,6 +397,10 @@
ci->ci_dev = self;
ci->ci_cpuid = cpunum;
+#if defined(__x86_64__) || defined(PAE)
+ mutex_init(&ci->ci_kpm_mtx, MUTEX_DEFAULT, IPL_VM);
KASSERT(HYPERVISOR_shared_info != NULL);
KASSERT(cpunum < XEN_LEGACY_MAX_VCPUS);
ci->ci_vcpu = &HYPERVISOR_shared_info->vcpu_info[cpunum];
@@ -547,10 +551,6 @@
/* No user PGD mapped for this CPU yet */
ci->ci_xen_current_user_pgd = 0;
-#if defined(__x86_64__) || defined(PAE)
- mutex_init(&ci->ci_kpm_mtx, MUTEX_DEFAULT, IPL_VM);