Re: [PATCH v2 2/4] m68k: Add support for M68040 CPU

Kuan-Wei Chiu
2025-12-29T14:45:38Z

Hi Daniel,

On Mon, Dec 29, 2025 at 10:54:45AM +0900, Daniel Palmer wrote:
> Hi Kuan-Wei,
>
> On Mon, 29 Dec 2025 at 04:29, Kuan-Wei Chiu <visitorckw@gmail.com> wrote:
> > > Connecting GDB and single stepping to work out where it is going would
> > > be helpful.
> >
> > I did attempt to investigate this using gdb, but unfortunately, the
> > root cause remains elusive. memset itself appears to execute correctly,
> > successfully zeroing out the global data. However, using it seems to
> > trigger a side effect where initcall_run_f() returns (which should not
> > happen), leading to the hang.
>
> Maybe a QEMU bug? If I get some time I will try to reproduce it.
>
> > > Since there is now a goldfish RTC driver upstream
> > > (drivers/rtc/goldfish_rtc.c) we could take the timer part from my
> > > version (https://github.com/fifteenhex/u-boot/blob/mc68000/drivers/rtc/goldfish_timer.c)
> > > and supply a real timer to the board. Right now I think anything that
> > > uses delays will get stuck constantly reading back 0?
> >
> > My original plan was to focus on a minimal boot to shell support in
> > this series and add rtc/timer support later. However, if you prefer to
> > have them included in this series, I am fine with that.
>
> I looked at adding the timer parts of my "goldfish rtc" driver to the
> upstream one and it's not very clean.
> So I have removed the unfinished RTC bits from my driver and moved the
> whole thing to drivers/timers/.
> That seems like a better way to go. I think having working delays etc
> would be nice even for the initial support.
> I guess if you send your initial stuff and someone asks "why is there
> no timer?" you can tell them I'll send a driver for that in the next
> series?

Sure, I will add rtc and timer support in the next version. Thanks!

>
> > Since the timer driver is authored by you, I assume I should add
> > Co-developed-by and Signed-off-by tags with your name to credit you
> > properly. I wanted to explicitly ask for your permission first.
>
> If there is anything in my branch you find useful you have my
> permission to just copy and paste without adding any tags etc.
> Credit is nice but I don't really mind.

Got it. Thanks.

>
> > Also, regarding the tags, would you prefer I send the integrated patch
> > to you privately for verification before posting v3, or is posting it
> > directly to the list fine?
>
> Can you put the branch on github or something for me? If you send me
> patches I'm going to have to import them to my local checkout to look
> at so if you have a branch I can access that's less steps. :D

Sure, I will push the series to github and share the link.

Regards,
Kuan-Wei