Re: [Qemu-devel] running out of Arm TB flags...

[Richard Henderson]

On 3/18/19 12:46 PM, Peter Maydell wrote:
> Hi; for the M-profile floating point work I'm going to need I think
> three new TB flags (to control whether to generate the code to do
> the various independent things the pseudocode ExecuteFPCheck() function
> does before executing any FP insn). Unfortunately we currently have
> only 2 unused bits in the arm TB flags word.
> 
> I can see two possible ways to get the 3rd bit:
> (1) overload the meaning of an existing bit which I know isn't
> relevant to M-profile (eg the XSCALE_CPAR or VECLEN or VECSTRIDE bits)
> (2) start defining new bits in the currently-unused cs_base word

Either works.  But I'd probably reuse (or eliminate) XSCALE_CPAR first.
Afaik, xscale never had vfp, so CPAR could overlap FPEXC_EL?


r~