[Qemu-devel] Re: [PATCH 2/3] target-ppc: fix default qNaN

[Alexander Graf]

On 02.01.2011, at 15:39, Aurelien Jarno wrote:

> On PPC the default qNaN doesn't have the sign bit set.

The spec says "don't care" for the sign bit. Did you extract the value 
empirically? I'm not saying it's wrong - the default 32 Bit value seems to be 
0x7FC0_0000 (2.06 ISA 6.6.2.2).

Hrm ... reading section 5.4.2:

A special QNaN is sometimes supplied as the default QNaN for a disabled 
invalid-operation exception; it has a plus sign, the leftmost 6 bits of the 
combination field set to 0b111110 and remaining bits in the combination field 
and the trailing significand field set to zero.

So I guess you're right.


Acked-by: Alexander Graf <address@hidden>


Alex