On Fri, 19 Feb 2016, Arnd Bergmann wrote: > On Thursday 18 February 2016 12:20:51 Nicolas Pitre wrote: > > On Thu, 18 Feb 2016, Arnd Bergmann wrote: > > > > > The gcc-4.9 optimization goes wrong while building target_core_iblock.c > > > for ARMv3 and leaves a bogus reference to __aeabi_uldivmod in the > > > output: > > > > > > ERROR: "__aeabi_uldivmod" [drivers/target/target_core_iblock.ko] > > > undefined! > > > > > > I could not find anyone who is interested in fixing it in gcc, > > > so as a workaround this disables the do_div magic, just like > > > we do for old compilers and for OABI. > > > > > > Signed-off-by: Arnd Bergmann <[email protected]> > > > > I suppose this is good enough for the purpose of keeping RiscPC > > buildable. Whether or not it is still used is another question. If it > > is then its user probably expects it to be slow already. > > > > Acked-by: Nicolas Pitre <[email protected]> > > Thanks. > > > Still unfortunate having to use a big hammer such as -march=armv3 just > > to avoid halfword memory accesses. > > I brought this up with the gcc developers before. They would really want > to deprecated ARMv3 support, but nobody seems interested in implementing > halfword memory access as a replacement.
Actually, the only thing needed as far as Linux on RiscPC is concerned is a compiler switch that prevents the use of STRH, LDRH and LDRSH instructions when -march=armv4 is used. > FWIW, I am currently still allowing ARMv3 in randconfig builds, but > have run into 12 internal compiler errors with that, on gcc-4.9 or higher. > It's probably all the same bug, but I don't see this getting fixed > unless the RiscOS people update to a newer toolchain and run into the > same problem. Hmmm I suppose the ability to use halfword accesses is assumed by new optimization patterns and that's why gcc fails when they're not available. > The patch below disables optimization so I am able to build this, but > I see no way to fix this upstream. That begs the question again: is anyone using mainline Linux on RiscPC? If I remember correctly, the ability to boot Linux on an i386 was removed a while ago and nobody complained. Nicolas
