Re: [PATCH] x86: Add .nop directive to assembler

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Feb 15, 2018 at 8:08 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> On 15.02.18 at 16:50, <matz@suse.de> wrote:
>> Hi,
>>
>> On Thu, 15 Feb 2018, Jan Beulich wrote:
>>
>>> >> to be an expression, none of the above is really suitable.
>>> >
>>> > Well, that could be easily rectified.  Something along the lines of:
>>>
>>> I didn't make the remark because of foreseeing any issues with
>>> coding this up, but because @NOP (or any of your other
>>> suggestions) could actually be a valid symbol name, which could be
>>> valid to use here even if it's not part of any expression in case it's
>>> an absolute one (e.g. an equate).
>>
>> Well, then I don't see other ways of special casing something that also is
>> a valid expression right now, like your string suggestion.  The problem of
>> course being that this would reinterpret currently valid (though
>> strange) directives into something else.  Right now
>>   .skip 10, "foo"
>> is equivalent to
>>   .skip 10, foo
>> and results in 10 one-byte relocs against symbol 'foo'.  We'd reinterpret
>> this, which may be fine, but needs to be a conscious decision.
>
> Oh, right, symbol names may be quoted now.
>
>>> The leading @ is undesirable anyway because of ARM's use of it as a
>>> comment char.
>>
>> Sure, other prefix chars could be used, e.g. one of the binary operators
>> in expressions.  But in light of the above it might not be such a bright
>> idea to extend .skip after all.
>
> Well, if we can fine a universally usable escape character, things
> ought to be fine this way. Apart from binary operator chars which
> aren't also unary operator ones, \ would come to mind.

I think we should simply go with

.nop SIZE


-- 
H.J.