10.0 RC5 panic after a clean buildworld on Hyper-V

[Jean-Luc Dupont]

Hello,

  We are upgrading our ESX to Hyper-V, and all our virtual FreeBSD will be running on Hyper-V.
For our POCs, we are testing all the releases of the 10.0 RCxx.

I installed 10.0 RC5 on a new virtual machine running on Hyper-V.
I svn checkout /base/stable/10

Without modifying neither the kernel nor the src.conf, I buildworld, buildkernel, installkernel, installworld.
After booting I had a kernel panic on attaching the storvsc.

I don't remember having this panic on older RCs of the 10.0

Here is the bt (OCRed):

cpuid = 0
KDB: stack backtrace:
#0 0xffffffff808d1670 at kdb_backtrace+0x60
#1 0xffffffff80899045 at panic+0x155
#2 0xffffffff80c73672 at trap_fatal+0x3a2
#3 0xffffffff80c73949 at trap_pfault+0x2c9
#4 0xffffffff80c730d6 at trap+0x5e6
#5 0xffffffff80c5a462 at calltrap+0x8
#6 0xffffffff80885ff0 at __mtx_unlock_sleep+0x60
#7 0xffffffff80885b4a at unlock_mtx+0x2a
#8 0xffffffff808a1c4e at _sleep+0x18e
#9 0xffffffff802dc2be at cam_periph_runccb+0x9e
#10 0xffffffff80cfe6f4 at storvsc_attach+0x6d4
#11 0xffffffff808c89e2 at device_attach+0x3a2
#12 0xffffffff80d0311b at hv_vmbus_child_deuice_register+0xdb
#13 0xffffffff80d01a33 at vmbus_channel_process_offer+0x133
#14 0xffffffff80d01576 at work_item_callback+0x26
#15 0xffffffff808df406 at taskqueue_run_locked+0xe6
#16 0xffffffff808dfc88 at taskqueue_thread_loop+0xa8
#17 0xffffffff8086b11a at fork_exit+0x9a
Uptime: 1s
Automatic reboot in 15 seconds - press a key on the console to abort

I tried to add hw.ata.disk_enable=1 in /boot/loader.conf without help.

Thank you for any advice.

Best regards