[RFA/gdbserver] x86 LynxOS-178: Adjust floating-point context structure

[Simon Marchi]

On 2018-05-10 11:05, Joel Brobecker wrote:
> The floating point context structure on x86 LynxOS-178 is not
> the same as on LynxOS 5.x. As a consequence, trying to print
> the return value of a function returning a float, for instance,
> yields incorrect results.
> 
> This patch fixes the issue by providing an updated definition
> for LynxOS-178 (the reason why we cannot access the actual definition
> provided by the system still remains true).
> 
> gdb/gdbserver/ChangeLog:
> 
>         * lynx-i386-low.c (LYNXOS_178): New macro.
>         (usr_fcontext_t) <LYNXOS_178>: Provide a definition that 
> matches
>         the layout on LynxOS-178.

This syntax (with < >) is usually meant to denote fields (as if you were 
referring to field LYNXOS_178 in structure usr_fcontext_t).  To denote 
an #ifdef context (which is what I understand you want to do), I usually 
see this syntax:

   [LYNXOS_178] (usr_fcontext_t): ...

For example:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gdb/ChangeLog-2017;h=aaadf142a4641ecd3feb26bc1dfa83dcc19e713c;hb=HEAD#l13806

>         (lynx_i386_fill_fpregset, lynx_i386_store_fpregset): Do not
>         handle floating point registers that are not supported by
>         LynxOS-178.
> 
> OK to push to master?

Otherwise, it looks good to me.

Simon