Current-Alpha6 panic with new support.S AMD64

With r338700 support.S i get panic after rebooting:

avail memory = 16529514496 (15763 MB)
MADT: Found CPU APIC ID 0 ACPI ID 1: enabled
SMP: Added CPU 0 (AP)
MADT: Found CPU APIC ID 2 ACPI ID 2: enabled
SMP: Added CPU 2 (AP)
MADT: Found CPU APIC ID 1 ACPI ID 3: enabled
SMP: Added CPU 1 (AP)
MADT: Found CPU APIC ID 3 ACPI ID 4: enabled
SMP: Added CPU 3 (AP)
Event timer "LAPIC" quality 100
kernel trap 9 with interrupts disabled


Fatal trap 9: general protection fault while in kernel mode
cpuid = 0; apic id = 00
instruction pointer	= 0x20:0xffffffff80747d86
stack pointer	        = 0x28:0xffffffff82451820
frame pointer	        = 0x28:0xffffffff82451820
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= resume, IOPL = 0
current process		= 0 ()
[ thread pid 0 tid 0 ]
Stopped at      strcmp+0x6:     movb    (%rsi),%dl
db> bt
Tracing pid 0 tid 0 td 0xffffffff81015180
strcmp() at strcmp+0x6/frame 0xffffffff82451820
sysctl_register_oid() at sysctl_register_oid+0x4c/frame 0xffffffff82451b40
sysctl_add_oid() at sysctl_add_oid+0x20d/frame 0xffffffff82451b90
et_register() at et_register+0x14d/frame 0xffffffff82451bf0
native_lapic_init() at native_lapic_init+0x4e3/frame 0xffffffff82451c10
madt_setup_local() at madt_setup_local+0x26e/frame 0xffffffff82451c40
apic_setup_local() at apic_setup_local+0x44/frame 0xffffffff82451c50
mi_startup() at mi_startup+0x118/frame 0xffffffff82451c70
btext() at btext+0x2c
db> 

With support.S r338683 no problem
Manfred