Re: Using parallel port on the Pegasos 2

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

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Ah I did not know about the relocation. Using 0x378 as the address works in
8.2.0. I do get the parallel_ioport_write messages now
parallel_ioport_write write [SW] addr 0x00 val 0x00

Quan


On Sun, Jul 28, 2024 at 5:33 PM BALATON Zoltan <balaton@eik.bme.hu> wrote:

> On Sun, 28 Jul 2024, quan wrote:
> > 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.
>
> Before implementing relocation of these devices they were at default port
> numbers in QEMU v8.2.0 so parallel was at 0x378. Did you try with that
> address? You can use 'info mtree' command in QEMU monitor to check which
> regions are enabled and where they are.
>
> Regards,
> BALATON Zoltan
>
> > 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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