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Description of problem:
Please add support to gdb and crash to decode the new CLFLUSHOPT instruction (in Intel Skylake and newer CPUs).  Currently gdb shows the 0x66 prefix as a separate instruction, but objdump decodes it correctly:

$ echo 'int main(void) { asm volatile("clflushopt (%rdi)"); }' > clflushopt.c
$ gcc -g clflushopt.c
$ objdump -d a.out | grep clflush
  4004f4:       66 0f ae 3f             clflushopt (%rdi)
$ gdb -q ./a.out
Reading symbols from /tmp/clflushopt/a.out...done.
(gdb) disas /r main
Dump of assembler code for function main:
...
   0x00000000004004f4 <+4>:     66      data16
   0x00000000004004f5 <+5>:     0f ae 3f        clflush (%rdi)


Version-Release number of selected component (if applicable):
gdb-7.6.1-78.el7
crash-7.1.2-2.el7

How reproducible:
always

Steps to Reproduce:
1. see above

Actual results:
   0x00000000004004f4 <+4>:     66      data16
   0x00000000004004f5 <+5>:     0f ae 3f        clflush (%rdi)

Expected results:
   0x00000000004004f4 <+4>:     66 0f ae 3f     clflushopt (%rdi)

Additional info:
See bug 1170846 comment 19 for where the issue was seen with crash

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-2328.html