Re: [Qemu-devel] [PATCH] Correct value of ARM Cortex-A8 MVFR1 register.

[Peter Maydell]

On 7 December 2016 at 17:14, Julian Brown <address@hidden> wrote:
> The value of the MVFR1 (Media and VFP Feature Register 1) register for
> the Cortex-A8 appears to be incorrect (according to the TRM, DDI0344K),
> with the "full denormal arithmetic" and "propagation of NaN" fields
> holding both 0 instead of both 1.
>
> I had a go tracing the history of the use of this value, and it seems
> it's always just been wrong in QEMU: maybe it was derived from early
> documentation, or guessed based on the use of a "VFP Lite" implementation
> in the Cortex-A8.
>
> Depending on the startup/early-boot code in use, this can manifest as
> failure to perform denormal arithmetic properly: in our case, selecting
> a Cortex-A8 CPU when using QEMU as an instruction-set simulator for
> bare-metal GCC testing caused tests using denormal arithmetic to
> fail. Problems might be masked (or not occur) when using a full OS kernel
> with suitable trap handlers (I'm not sure).
>
> Signed-off-by: Julian Brown <address@hidden>

Applied to target-arm.next for 2.9, thanks.

-- PMM