The otp_src_R12B-0-osp1.patch fixes the following issues present
in otp_src_R12B-0:

OTP-7006  The SMP emulator on sparc64 erroneously used the sparc32
          atomic and the sparc32 spinlock implementations which
          caused it to crash.

OTP-7012  Matching an empty binary in a record and then using the
          same record again could cause a compiler crash.

          Example code that triggers the crash:

          -record(r, {a,b}).
          t(R) ->
            #r{a = <<>>} = R,
            R#r.b.

OTP-7013  file:read/2 and file:consult_stream/1,3 did not use an empty
          prompt on I/O devices. This bug has now been corrected.

OTP-7014  configuring --enable-darwin-universal or --enable-darwin-64bit
          on MacOSX could result in a non optimized emulator. Top level
          configure script now corrected.

OTP-7015  configuring --with-gd did not produce correct include flags
          for percept.


How to apply the patch:
  $ ls
  otp_src_R12B-0-osp1.patch   otp_src_R12B-0.tar.gz
  $ gtar -zxf otp_src_R12B-0.tar.gz 
  $ patch -ZNp0 < otp_src_R12B-0-osp1.patch 
  patching file `otp_src_R12B-0/configure'
  patching file `otp_src_R12B-0/configure.in'
  patching file `otp_src_R12B-0/erts/aclocal.m4'
  patching file `otp_src_R12B-0/erts/config.h.in'
  patching file `otp_src_R12B-0/erts/configure'
  patching file `otp_src_R12B-0/erts/configure.in'
  patching file `otp_src_R12B-0/erts/include/internal/ethread.h'
  patching file `otp_src_R12B-0/erts/include/internal/ethread_header_config.h.in'
  patching file `otp_src_R12B-0/erts/lib_src/common/ethread.c'
  patching file `otp_src_R12B-0/lib/compiler/src/v3_codegen.erl'
  patching file `otp_src_R12B-0/lib/kernel/src/file.erl'
  $ cd otp_src_R12B-0
  $ # configure, make, and make install as usual...