Messages in this thread |  | | From | David Mosberger <> | Date | Wed, 12 May 2004 11:13:50 -0700 | Subject | Re: GCC nested functions? |
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>>>>> On Wed, 12 May 2004 10:59:24 -0700, Stephen Hemminger <shemminger@osdl.org> said:
Stephen> I used GCC nested functions in the (not released) bridge Stephen> sysfs interface for 2.6.6. It seemed like a nice way to Stephen> express the sysfs related interface without doing lots of Stephen> code copying (or worse lots of macros).
Oh, man! Nested C functions are evil. Just don't do it.
Stephen> This works fine for GCC 2.95 and 3.X for i386 and x86_64 Stephen> architectures, but the ia64 (cross compiler) pukes with:
Stephen> In function `store_forward_delay': Stephen> : undefined reference to `__ia64_trampoline'
Stephen> Redoing it as separate functions is easy enough, but the Stephen> questions are:
Stephen> - Are gcc nested functions allowed in the kernel? If not Stephen> where should this restriction be put in Documentation? Stephen> CodingStyles?
Nested C functions shouldn't be allowed _anywhere_. It's the worst extension that has made it into GNU C.
Stephen> - Or is gcc on ia64 just too stupid? or do some more Stephen> support routines need to exist in arch/ia64?
It has nothing to do with stupidity. The kernel doesn't support all the routines provided by libgcc.a. __ia64_trampoline() is one of them.
Stephen> - Do other architectures (sparc, ppc) have similar problems?
It's not a problem. It's a feature. It's likely that other architectures which require a helper-routine from libgcc would behave the same.
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