Re: Using parallel port on the Pegasos 2

[quan <qeed.quan@gmail.com>]

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I have tried this on qemu 8.2.0 (I downloaded it and compiled with
--enable-debug), this build does not seem to hit the breakpoint
portio_write function when writing to 0x3bc while it does on the latest
qemu git version.

Using the  trace:memory_region_ops_write option for 8.2.0, the other
devices like serial and rtc does get hit, but it never prints a write for
'parallel', as if its disabled somehow.

Quan

On Sun, Jul 28, 2024 at 2:17 PM BALATON Zoltan <balaton@eik.bme.hu> wrote:

> On Sun, 28 Jul 2024, quan wrote:
> > I am playing around with the parallel port on the pegasos 2 and I noticed
> > the following issue:
> > The parallel port on startup is set to iobase 0x378, then later it gets
> > remapped to iobase 0x3bc.
> > When I tried writing to the 0x3bc location with
> > trace:memory_region_ops_write on, I get logs about writing to the
> location
> > 'parallel', so far so good, but the writes don't make it through (it
> never
> > calls parallel_ioport_write* functions)
> >
> > I traced it through where it calls portio_write, and inside the
> > portio_write code:
> > This line always fails for me:
> > const MemoryRegionPortio *mrp = find_portio(mrpio, addr, size, true);
> > This is due to the mrpio has the offset of 0x44 (0x3bc-0x378) in the
> list,
> > and the 'addr' in the code ranges from (0-15) (address relative to
> 0x3bc),
> > so it can never match the parallel io function to execute.
> >
> > This seems like a bug to me. I think there is some issue where the
> > portio_list is not getting updated properly after the remapping to 0x3bc.
> >
> > The other devices (Serial, RTC, PM, VGA) responds properly for me, so it
> is
> > only the parallel port that has this issue.
>
> Is this something that broke recently or can the same be reproduced with
> QEMU v8.2.0. The relocation of these devices was implemented around commit
> 35a6380b4ed27f (and the ones before that). Adding Bernhard to cc as well.
>
> Regards,
> BALATON Zoltan
>

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