[PATCH] configure.ac: Remove unreachable check for VM86 headers.

Jamey Sharp jamey at minilop.net
Thu Sep 15 20:22:05 PDT 2011

On Thu, Sep 15, 2011 at 07:28:25PM -0400, Gaetan Nadon wrote:
> On Wed, 2011-09-14 at 10:07 -0500, Jamey Sharp wrote:
> > "configure --with-int10=yes" is not a valid configuration, and the check
> It depends what is the definition of "valid" in this context. Running
> "./configure --with-int10" will set "INT10" to "yes". You may choose to
> ignore this value. I can only guess that current code checked for "yes"
> as a means to provide a default value when no backend was specified.

On further investigation: Daniel Stone introduced the block I'm
proposing to delete in commit 588105173840355717d7b2f7f652289a41166c3f
from 2005, with a commit message beginning "Huge cleanup." It appears
that he intended that patch to mostly be a reorganization of
configure.ac, not to change functionality, so I'm not sure how this
snuck in.

Otherwise, as far as I can tell, there's never been an attempt to
support INT10=yes.

> > for sys/vm86.h and sys/io.h is not used. Delete it.
> I agree with ignoring "yes". I don't recall any other module using it in
> that way. Just be prepared in the case where someone did use it. It's
> not really dead code, but close enough.
> The default value is either x86emu or stub for FreeBSD on a PowerPC. Any
> unrecognized value (such as yes, no or vn86) will not build any int10
> backend. No warnings or errors. Hopefully the builder will have some way
> of finding out why it does not work. The library builds with just the
> common code.

"vn86" is an excellent example. This does seem error-prone. But:

> Suggestion:
>         AS_HELP_STRING([--with-int10=BACKEND], [vm86, x86emu or stub (default:auto)]),
>         AC_MSG_ERROR if no valid value is given

Can you suggest a patch that does that? I don't see any way to report
such an error without copying the list of possible backends yet another

>         Verify if there is a need to check for the headers. The code as
>         it is was probably the result of changes around it rather than
>         the intention of the developer.

Not as far as I can tell; and since nobody could have gotten a usable
int10 module with --with-int10, and the AC_CHECK_HEADERS is only used in
that case, I don't think anybody is relying on it.

So is there some reason not to apply this patch as-is?

Thanks for looking this over!
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