mbrprobe: dev=vn0 blksize=0x40000 blocks=64 media_size=16777216
panic: assertion "(int)info->d_media_blksize <= bp->b_bufsize" failed in mbrinit at /usr/src/sys/kern/subr_diskmbr.c:128
cpuid = 0
Trace beginning at frame 0xfffff80117fa36a8
mbrinit() at mbrinit+0x4fa 0xffffffff80b971da 
mbrinit() at mbrinit+0x4fa 0xffffffff80b971da 
mbrprobe_modevent() at mbrprobe_modevent+0xd2 0xffffffff826010d2 
module_register_init() at module_register_init+0x49 0xffffffff806232e9 
linker_load_file.part.3() at linker_load_file.part.3+0x1b9 0xffffffff80624619 
linker_load_module() at linker_load_module+0x116 0xffffffff80625e16 
Debugger("panic")

CPU0 stopping CPUs: 0x0000003e
 stopped
Stopped at      Debugger+0x7c:  movb    $0,0xbdaf09(%rip)
db>