On Sat, Oct 16, 2010 at 10:04:59AM +0200, Geert Uytterhoeven wrote: > > -const unsigned long mips_io_port_base __read_mostly = -1; > > +const unsigned long mips_io_port_base = -1; > > EXPORT_SYMBOL(mips_io_port_base); > > Ugh. So as soon as someone implements MMU protection for the read-only data > section, it'll break silently? That's not the only failure mode. A const might be replicated by a compiler for example into multiple small data sections or by loading the rodata into multiple NUMA nodes. The later hits IP27 but that one got potencially many PCI busses anyway, so mips_io_port_base was always problematic. From the time I put this optimization hack in it was clear that I was gaming GCC and sooner or later it was going to blow up. It's held for like a decade so I got my money's worth :) Ralf
