Re: [PATCH] BUG preserve registers

[Andrew Morton <akpm@zip.com.au>]

Linus Torvalds wrote:
> 
> On Sat, 9 Feb 2002, Andrew Morton wrote:
> > >
> >
> > Is better, except the filename gets expanded multipe times into
> > the object file.  How about:
> >
> > #define BUG()                   \
> >         asm(    "ud2\n"         \
> >                 "\t.word %0\n"  \
> >                 "\t.long %1\n"  \
> >                  : : "i" (__LINE__), "i" (__FILE__))
> 
> Even better.
> 
> That way you can actually totally remove the "verbose bug" config option,
> because even the verbose BUG's aren't actually using up any noticeable
> amounts of space.
> 
> This is all assuming that gcc doesn't create the string for inline
> functions that aren't used, which it probably cannot, so maybe this
> doesn't work out.
> 

gcc generally get it wrong - unreferenced strings still appear
in the object code from multiple usage patterns.  I think this
was fixed about six months ago.

But yes, the verbose BUG overhead is now six bytes per BUG, plus
a few bytes per file for the filename.  And it's my opinion that
the non-verbose BUG option is undesirable - it's making the
developers' job harder.  Seems that with this change, the reasons
for CONFIG_DEBUG_BUGVERBOSE are no longer with us, and it can
disappear.

-