Re: Deprecate the ppc405 boards in QEMU?

[Greg Kurz]

On Tue, 19 Oct 2021 11:31:03 +0200
Christophe Leroy <christophe.leroy@csgroup.eu> wrote:

> 
> 
> Le 11/10/2021 à 15:24, Thomas Huth a écrit :
> > On 11/10/2021 11.20, David Gibson wrote:
> >> On Mon, Oct 11, 2021 at 10:10:36AM +0200, Thomas Huth wrote:
> >>> On 06/10/2021 09.25, Thomas Huth wrote:
> >>>> On 05/10/2021 23.53, BALATON Zoltan wrote:
> >>>> [...]
> >>>>> Maybe these 405 boards in QEMU ran with modified firmware where the
> >>>>> memory detection was patched out but it seems to detect the RAM so I
> >>>>> wonder where it gets that from. Maybe by reading the SDRAM
> >>>>> controller DCRs ppc4xx_sdram_init() sets up. Then I'm not sure what
> >>>>> it needs the SPD for, I forgot how this worked on sam460ex. Maybe
> >>>>> for the speed calibration, so could be it detects ram by reading
> >>>>> DCRs then tries to get SPD data and that's where it stops as i2c is
> >>>>> not emulated on taihu. This could be confirmed by checking what it
> >>>>> pokes with -d guest_errors that shows accesses to missing devices
> >>>>> but don't know where 405 has the i2c controller and if it's the same
> >>>>> as newer SoCs. If so that could be reused and an i2c bus could be
> >>>>> added with the SPD data like in sam460ex to make u-boot happy or you
> >>>>> could skip this in u-boot.
> >>>>
> >>>> FWIW, I've just tried the latter (skipping the sdram init in u-boot),
> >>>> and indeed, I can get to the u-boot prompt now.
> >>> [...]> I've also attached the patch with my modifications to u-boot.
> >>>
> >>> FYI, the changes can now be found on this branch here:
> >>>
> >>>   https://gitlab.com/huth/u-boot/-/commits/taihu
> >>>
> >>> I also added a gitlab-CI file, so you can now download the u-boot.bin 
> >>> as an
> >>> artifact from the corresponding pipeline, e.g.:
> >>>
> >>>   https://gitlab.com/huth/u-boot/-/jobs/1667201028
> >>
> >> Thanks.
> >>
> >> Are you going to send a v2 of your proposed deprecation patches?
> > 
> > No, since there was interest in keeping the 405 boards for testing the 
> > 405 code in the Linux kernel, and since there is now a way to do at 
> > least some very basic testing of these boards (with the u-boot 
> > firmware), I don't plan to respin the deprecation patch. I just sent a 
> > patch for adding the boards to our CI instead:
> > 
> >   https://lists.gnu.org/archive/html/qemu-devel/2021-10/msg02072.html
> > 
> 
> I have downloaded your u-boot.bin and tried it with both QEMU 5.2.0 and 
> mainline, and I get:
> 
> ERROR:../accel/tcg/tcg-accel-ops.c:79:tcg_handle_interrupt: assertion 
> failed: (qemu_mutex_iothread_locked())
> Bail out! ERROR:../accel/tcg/tcg-accel-ops.c:79:tcg_handle_interrupt: 
> assertion failed: (qemu_mutex_iothread_locked())
> Abandon (core dumped)
> 
> I see in the mail history that you got that problem as well at some 
> point. How did you fix it ?
> 

https://lists.gnu.org/archive/html/qemu-devel/2021-10/msg01019.html

Not yet upstream but already in David's ppc-for-6.2 tree :

https://gitlab.com/dgibson/qemu/-/commit/c29fca5c8173e9e647ebff07cb78b7c8135bd11a

> Thanks
> Christophe