Re: [RFC 2/7] Add unit test to builtin tdesc generated by xml

[Yao Qi <qiyaoltc@gmail.com>]

Philipp Rudo <prudo@linux.vnet.ibm.com> writes:

Hi Philipp,
Thanks for your comments.

> The only thing you could have done to make it better is to get rid of the
> conversion to C altogether and create the target description directly by
> parsing the XML file. I don't see a benefit in the conversion and removing it
> would simplify the code even more.  But that is a long term goal and your patch
> set definitely helps towards that goal.

As I described in the commit log, "the reason that we transform xml files
to c files is that GDB is still able to have some target description
without xml parsing support." so that XML parsing is not a hard
requirement for GDB.  Nowadays, XML parsing is only used for remote
debugging.  In native debugging, GDB just uses these pre-generated
builtin target descriptions, without parsing any XML.

Suppose XML parsing is always there, at least on Linux host, GDB can
create a big buffer contains various target features in the runtime.  We
can do this on top of patch 6/7, like this, (take i386-linux as an
example),

/* Return a string having XML contents reflecting the right target
   description according to XCR0.  */

std::string
i386_linux_read_description (uint64_t xcr0)
{
   std::string buffer;

   buffer.append ("<?xml version="1.0"?>");
   buffer.append ("<!DOCTYPE target SYSTEM "gdb-target.dtd">");
   buffer.append ("<target>");
   buffer.append ("  <architecture>i386</architecture>");
   buffer.append ("  <osabi>GNU/Linux</osabi>");

   if (xcr0 & X86_XSTATE_X87)
     {
        /* Open 32bit-core.xml and copy its content here.  */
     }

   if (xcr0 & X86_XSTATE_SSE)
     {
       /* Open 32bit-sse.xml and copy its content here.  */
     }

    ....

   buffer.append ("</target>");

   return buffer;
}

Even further, this code can be shared between GDB and GDBserver, so that
GDBserver can compose the XML contents and send it to GDB.  Note that
GDBserver doesn't need to parse the XML.

-- 
Yao (齐尧)