Re: arch/mips/sgi-ip22/Platform:29: *** gcc doesn't support needed option -mr10k-cache-barrier=store. Stop.

[Ralf Baechle <ralf@linux-mips.org>]

On Wed, Apr 09, 2014 at 07:44:42PM -0400, Joshua Kinard wrote:

> > I notice there is also a mips64 compiler. Should I use that?

The difference between a mips-linux, mips64-linux, mips64el-linux or mipsel-linux
compiler are only the defaults and they can be overridden with command
line options; the kernel makefiles will pass the required options.

> If you weren't using a mips64 compiler, that's probably the issue.  R10000
> processors are 64-bit only, so a 'mips' toolchain probably doesn't include
> the R10K cache-barrier code, causing that option to fail.

No - there's no mode switch.  An R10000 will happily run 32-bit code
otherwise 32 bit kernels wouldn't work.  32 bit code just doesn't use
64 bit addressing, instructions or the upper 32 bit of the 64 bit registers.

$ mips-linux-gcc -mr10k-cache-barrier=store -c -O2 -o c.o c.c
c.c:1:0: error: ‘-mr10k-cache-barrier’ requires a target that provides the ‘cache’ instruction
[...]

When adding an option like -mips32 the compilation will succeed.

> Are you configuring for IP22 (Indy, Indigo2 R4x00), or IP28 (R10000)?  Note,
> IP26 (R8000) is not supported in Linux.  I think OpenBSD got it working, though.

Wish I'd have a box ....

  Ralf