[PATCH RESEND] x86: allow VEX et al encodings in 16-bit (protected) mode

[Jan Beulich]

>>> On 24.06.19 at 18:30, <hjl.tools@gmail.com> wrote:
> On Mon, Jun 24, 2019 at 7:05 AM Jan Beulich <JBeulich@suse.com> wrote:
>> --- a/gas/config/tc-i386.c
>> +++ b/gas/config/tc-i386.c
>> @@ -4387,9 +4387,9 @@ md_assemble (char *line)
>>
>>    if (is_any_vex_encoding (&i.tm))
>>      {
>> -      if (flag_code == CODE_16BIT)
>> +      if (!cpu_arch_flags.bitfield.cpui286)
>>         {
>> -         as_bad (_("instruction `%s' isn't supported in 16-bit mode."),
>> +         as_bad (_("instruction `%s' isn't supported outside of protected mode."),
>>                   i.tm.name);
>>           return;
>>         }
> 
> flag_code == CODE_16BIT is used to indicate 16-bit mode, in most cases, for real
> mode.   If there are real use cases for VEX/EVEX insns in 16-bit protected mode,
> should we add a directive or pseudo prefix to indicate protected mode encoding?

Not sure - I'd leave that to you. All I want/need is to be able encode
VEX/XOP/EVEX insns for 16-bit protected mode use. How about we go
with this patch for now, and you further refine things to your liking
subsequently?

Jan