[Libre-soc-dev] mp3 changes

[Luke Kenneth Casson Leighton]

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crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68


On Fri, May 28, 2021 at 10:15 AM Lauri Kasanen <cand at gmx.com> wrote:

> On Fri, 28 May 2021 12:13:20 +0300
> Lauri Kasanen <cand at gmx.com> wrote:
>
> > Hi,
> >
> > Luke, you're breaking my stuff with all the qemu changes. I'm
> > considering reverting them.
>

apologies, i'm half-way through moving the stack and etc. to
different locations that don't conflict with the location that
qemu has (i think) placed the skiboot BIOS.

also, the stack location definitely risks conflict with the location that
exceptions are at: 0x500, 0x700, 0x800, 0x900 etc.

this _might_ be solved simply by... oh,                   '-machine',
'powernv9'
non-virtualised power9 is already the option used.


> Or rather, if you need a different mem map for qemu, please put those
> to separate files instead of changing the current ones.
>

does the stack location and memory location matter to you?
(as long as i finish the offset-changes to mp3_1.sh which i
had completed on mp3_0.sh)

the instruction that's causing an exception is stfd (only the 4th one
executed) .... oh ha ha
https://github.com/antonblanchard/microwatt/blob/84473eda1b54a03794b2f3d13748f42b52ead34e/execute1.vhdl#L791

0x800 is an FPU exception.  i hadn't realised that, thougth it was a
straight LD/ST one.

i *think* it might be necessary to set the MSR FP bit, it could be as
simple as that.

yes, please do put the memory locations back, but do consider putting the
stack
much higher up.

l.