Re: [Xen-devel] xen on beagleboard-x15: fails to access PRCM MPU register

[Iain Hunter <drhunter95@xxxxxxxxx>]

Hi Denis,
Agreed. I would continue as you are, just remembering that if you have
an issue there might be a patch for it already and have a look at the
patches.
Iain

On Fri, 28 Jun 2019 at 19:31, Denis Obrezkov <denisobrezkov@xxxxxxxxx> wrote:
>
> Hi Iain,
>
> On 6/28/19 7:25 PM, Iain Hunter wrote:
> > Hi Stefano,
> > It was a patchset I'd circulated earlier in the GSoC process.
> > Basically the partial port of Xen on X15 I'd done last year. The build
> > script is the reference for which patches were actually used.
> > Iain
> I believe the reason we haven't started from trying your patch was that
> I thought that since you hadn't used smp your solution might not work in
> our case, since we want to have smp (I was probably wrong).
> I think I should reproduce all the issues step-by-step that Iain faced
> and apply his patches where they are required (otherwise it would be
> hard for me to understand what's happening).
>
> Stefano, Julien?
> >
> > On Fri, 28 Jun 2019 at 17:02, Stefano Stabellini <sstabellini@xxxxxxxxxx> 
> > wrote:
> >>
> >> Hi Iain,
> >>
> >> Where is the patch you mentioned? Maybe you forgot to attach it to the
> >> email?
> >>
> >> Cheers,
> >>
> >> Stefano
> >>
> >> On Fri, 28 Jun 2019, Iain Hunter wrote:
> >>> Stefano, Denis,
> >>>
> >>> I achieved that with patch
> >>> patches/xen/0003-add-PRCM_MPU-to-memory-translation-for-AM572x.patch.
> >>> This just adds
> >>>  .specific_mapping=omap5_specific_mapping
> >>> to DRA7 platform.
> >>>
> >>> Iain
> >>>
> >>> On Fri, 28 Jun 2019 at 01:33, Stefano Stabellini <sstabellini@xxxxxxxxxx> 
> >>> wrote:
> >>>>
> >>>> Writing here a summary of the follow-up discussion on IRC.
> >>>>
> >>>> This is due to a magic memory region, not described in the device tree,
> >>>> being accessed by Linux. The memory region is 0x48243400 - 
> >>>> 0x48243400+512.
> >>>>
> >>>> To fix problems like this one, we have the platform specific files in
> >>>> xen: see the files under xen/arch/arm/platforms/. Specifically, omap5.c
> >>>> might be a good model for what we need. Look at the
> >>>> omap5_specific_mapping function, which does exactly what the name
> >>>> suggests: it maps special MMIO regions into the guest.
> >>>>
> >>>>  /* Additional mappings for dom0 (not in the DTS) */
> >>>>  static int omap5_specific_mapping(struct domain *d)
> >>>>  {
> >>>>      /* Map the PRM module */
> >>>>      map_mmio_regions(d, gaddr_to_gfn(OMAP5_PRM_BASE), 2,
> >>>>                       maddr_to_mfn(OMAP5_PRM_BASE));
> >>>>
> >>>>      /* Map the PRM_MPU */
> >>>>      map_mmio_regions(d, gaddr_to_gfn(OMAP5_PRCM_MPU_BASE), 1,
> >>>>                       maddr_to_mfn(OMAP5_PRCM_MPU_BASE));
> >>>>
> >>>>      /* Map the Wakeup Gen */
> >>>>      map_mmio_regions(d, gaddr_to_gfn(OMAP5_WKUPGEN_BASE), 1,
> >>>>                       maddr_to_mfn(OMAP5_WKUPGEN_BASE));
> >>>>
> >>>>      /* Map the on-chip SRAM */
> >>>>      map_mmio_regions(d, gaddr_to_gfn(OMAP5_SRAM_PA), 32,
> >>>>                       maddr_to_mfn(OMAP5_SRAM_PA));
> >>>>
> >>>>      return 0;
> >>>>  }
> >>>>
> >>>> We need something similar for 0x48243400 - 0x48243400+512 on
> >>>> Beagleboard.
> >>>>
> >>>>
> >>>> On Thu, 27 Jun 2019, Denis Obrezkov wrote:
> >>>>> CC'ed other GSoC mentors
> >>>>>
> >>>>> On 6/27/19 9:52 PM, Denis Obrezkov wrote:
> >>>>>> Hello all,
> >>>>>>
> >>>>>> I have a failure when I am trying to boot Linux with Xen on bb-x15, 
> >>>>>> here
> >>>>>> is the log:
> >>>>>> https://pastebin.com/BBAFPkVU
> >>>>>>
> >>>>>> and, as Julien (cc'ed) suggested here is the DT debug information for 
> >>>>>> xen:
> >>>>>> https://drive.google.com/open?id=15YTsCKYUTbG2i-siWezJXKWuG0H1VfQz
> >>>>>>
> >>>>>> So, what I was able to figure out:
> >>>>>> In omap4_prminst_read_inst_reg it tries to read from 
> >>>>>> _prm_bases[part].va
> >>>>>> (arch/arm/mach-omap2/prminst44xx.c).
> >>>>>> _prm_bases[part].va has a value of prm_base or prcm_mpu_base depending
> >>>>>> on part value(arch/arm/mach-omap2/prminst44xx.c:44)
> >>>>>> Failure happens when _prm_bases[OMAP4430_PRCM_MPU_PARTITION] is read.
> >>>>>> It's value set up in arch/arm/mach-omap2/prcm_mpu44xx.c:54.
> >>>>>> The installed value is obtained with OMAP_L4_IO_ADDRESS macro
> >>>>>> (mach_omap2/io.c:667). Here is its definition 
> >>>>>> (arch/arm/mach_omap2/iomap.h):
> >>>>>> #define OMAP2_L4_IO_OFFSET  0xb2000000
> >>>>>> #define OMAP2_L4_IO_ADDRESS(pa) IOMEM((pa) + OMAP2_L4_IO_OFFSET) /* L4 
> >>>>>> */
> >>>>>>
> >>>>>> and IOMEM (arch/arm/include/asm/io.h):
> >>>>>> #define IOMEM(x)    ((void __force __iomem *)(x))
> >>>>>>
> >>>>>> I don't understand what is happening and how to overcome it.
> >>>>>>
> >>>>>
> >>>>> --
> >>>>> Regards, Denis Obrezkov
> >>>>>
> >>>>>
> >>>
>
> --
> Regards, Denis Obrezkov
>

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