Re: [Xen-devel] [PATCH for-4.8] ipxe: update to newer commit

[Ian Jackson <ian.jackson@xxxxxxxxxxxxx>]

Boris Ostrovsky writes ("Re: [Xen-devel] [PATCH for-4.8] ipxe: update to newer 
commit"):
> We could but what if an old compiler doesn't support that option?
> Although it looks like -Wno-<option>, which is what we'd use, may be OK:
> 
> ostr@workbase> gcc foo.c
> ostr@workbase> gcc -Wfoo foo.c
> gcc: error: unrecognized command line option ‘-Wfoo’; did you mean ‘-Wno-’?
> ostr@workbase> gcc -Wno-foo foo.c
> ostr@workbase>

Many many years ago I filed a bug asking the gcc folks to make
 -Wno-some-random-warning-option-that-gcc-does-not-know-about
not be an error.

That was eventually done.  I'm not sure exactly when the change was
made.  Does gcc -Wno-foo work properly on all the gcc's we care about ?

> >> Another interesting new warning that is fatal with -Werror is
> >>     if(a)
> >>         foo();
> >>         bar();
> >>
> >> gcc warns that bar() is indented and maybe braces are needed.
> > Do we actually have cases like this ?  Are they real bugs ?
> 
> Yes we have (for example igb_phy.c change in the patch that I sent) and
> no, they don't look like bugs.

I guess we can disable that warning too then.

> >> BTW, another option for backporting may be removing -Werror. If we know
> >> we are not changing sources then we might consider this.
> > Perhaps we could disable warnings more selectively.
> 
> I scanned the changes again and at least one appears to be fixing a
> legitimate bug (buffer overrun). There is an upstream patch for that,
> which is essentially what I have there, but not as a separate patch.

I don't think a buffer overflow in ipxe is any kind of problem.  The
_whole purpose_ of ipxe is to take unauthenticated data from the
network and unconditionally execute it...

Ian.

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