Re: [arm-gnu] Advanced SIMD instruction support

[Mark Mitchell <mark@xxxxxxxxxxxxxxxx>]

Akshay Joshi wrote:

> 	I am trying to enable Advanced SIMD and VFP in the linux kernel by setting
> the FPEXC.EN bit.
> To set that bit I am using the VMSR instruction. But the assembler gives
> "bad instruction: vmsr fpexc, r1" error.
> Are the vmsr / vmrs instructions supported by the toolchain?

The assembler doesn't know about the VMSR opcode.  (I've checked the
documentation we have from ARM and I don't see a mention of that opcode.
 It's mentioned on ARM's website, but I don't see any documentation of
the actual assembly encoding.)  Do you have a non-NDA reference you can
point to regarding VMSR?

However, the "msr" instruction in the GNU assembler does accept fpexc:

  msr fpexc, r1

is encoded as:

  8:   eee81a10        fmxr    fpexc, r1

Is that the instruction you need?

-- 
Mark Mitchell
CodeSourcery
mark@xxxxxxxxxxxxxxxx
(650) 331-3385 x713