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

[Iain Hunter <drhunter95@xxxxxxxxx>]

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

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
> > > >
> > > >
> >

Attachment: gsoc-xen-v0.1.tar.gz
Description: GNU Zip compressed data

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