Re: [Qemu-devel] [PATCH] sun4u: add power_mem_read routine

[Mark Cave-Ayland]

On 04/01/2019 05:47, P J P wrote:

>   Hello Mark,
> 
> +-- On Thu, 3 Jan 2019, Mark Cave-Ayland wrote --+
> | >  /* Power */
> | > +static uint64_t power_mem_read(void *opaque, hwaddr addr, unsigned size)
> | > +{
> | > +    return 0xffffffff;
> | > +}
> | > +
> | >  
> | >  static const MemoryRegionOps power_mem_ops = {
> | > +    .read = power_mem_read,
> | >      .write = power_mem_write,
> | >      .endianness = DEVICE_NATIVE_ENDIAN,
> | >      .valid = {
> | 
> | Certainly the addition of the missing read function is valid, although I 
> see that
> | you've defaulted reads to returning 0xffffffff - can you point me towards 
> the source
> | that indicates that this behaviour matches that of real Ultra-5 hardware?
> 
>  -> https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg02787.html
> 
> I haven't checked Ultra-5 h/w spec, return value was chosen similar to above 
> one, thinking unimplemented .read need not return success.
> 
> Thank you.

I asked someone with real Ultra-5 hardware to check this for me, and they've 
sent me
back the following output:

ok .properties
address                  fffb8000
button
interrupts               00000001
reg                      00000014 00724000 00000004
name                     power
ok fffb8000 l@ u.
0

Looks like the read value should be all 0s rather than all 1s. Can you resubmit 
the
patch with this change?


ATB,

Mark.