Hello,
since I wrote the NetBSD code in question, here are my 2 cent:
On Sat, 29 Aug 2020 08:41:43 -0700
Richard Henderson <richard.henderson@linaro.org> wrote:
> On 8/22/20 7:21 AM, Philippe Mathieu-Daudé wrote:
> > The S24/TCX datasheet is listed as "Unable to locate" on [1].
I don't have it either, but someone did a lot of reverse engineering
and gave me his notes. The hardware isn't that complicated, but quite
weird.
> > However the NetBSD revision 1.32 of the driver introduced
> > 64-bit accesses to the stippler and blitter [2]. It is safe
> > to assume these memory regions are 64-bit accessible.
> > QEMU implementation is 32-bit, so fill the 'impl' fields.
IIRC the real hardware *requires* 64bit accesses for stipple and
blitter operations to work. For stipples you write a 64bit word into
STIP space, the address defines where in the framebuffer you want to
draw, the data contain a 32bit bitmask, foreground colour and a ROP.
BLIT space works similarly, the 64bit word contains an offset were to
read pixels from, and how many you want to copy.
Thanks Michael for this information!
If you don't mind I'll amend it to the commit description so there is a reference for posterity.
I'm waiting for Andreas Gustafsson to test it then will repost.