What this "arw" line means when processing Mach-0 file with Radare2 or Rabin2?

Question

Processing a Mach-0 file with Rabin2 I'm obtaining the following result:

$ rabin2 -I mybinaryfile
arw 00000000000000000000000000000000000000000000000000000000000000001f0000000000000000000000170000001f0000001f0000000000000000000000
arch     x86
baddr    0x0
binsz    69256
bintype  mach0
bits     32
canary   false
sanitiz  false
class    MACH0
crypto   false
endian   little
havecode true
laddr    0x0
lang     c++
linenum  false
lsyms    false
machine  386
maxopsz  16
minopsz  1
nx       false
os       darwin
pcalign  0
pic      false
relocs   false
static   true
stripped false
subsys   darwin
va       true

Opening it with Radare2 the same "arw" line appears:

$ radare2 mybinaryfile
arw 00000000000000000000000000000000000000000000000000000000000000001f0000000000000000000000170000001f0000001f0000000000000000000000
 -- radare2-built farm beats the facebook one.
[0x00000000]> 

[0x00000000]> ih
0x00000000  Magic       0xfeedface
0x00000004  CpuType     0x7
0x00000008  CpuSubType  0x3
0x0000000c  FileType    0x1
0x00000010  nCmds       3
0x00000014  sizeOfCmds  840
0x00000018  Flags       0x2000
0x00000020  cmd       0 0x1 LC_SEGMENT
0x00000024  cmdsize     736
0x00000300  cmd       1 0x2 LC_SYMTAB
0x00000304  cmdsize     24
0x00000318  cmd       2 0x5 LC_UNIXTHREAD
0x0000031c  cmdsize     80

I've searched but I didn't find any answer. What does this "arw" line mean?

Answer 1

It looks like it's a raw byte dump of an arch-specific thread_state structure (e.g. for 32bit x86). See here for where the dump happens.