Re: Deprecate the ppc405 boards in QEMU?

[Thomas Huth]

On 19/10/2021 11.31, Christophe Leroy 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 ?

You need this patch here to fix this issue:

 https://lists.gnu.org/archive/html/qemu-devel/2021-10/msg01019.html
 ("hw/ppc: Fix iothread locking in the 405 code")

 Thomas