Hi Julien, On Mon, May 13, 2019 at 11:20 AM Julien Grall <julien.gr...@arm.com> wrote: > On 5/10/19 5:22 PM, Oleksandr Tyshchenko wrote: > > From: Oleksandr Tyshchenko <oleksandr_tyshche...@epam.com> > > > > Don't use hardcoded address, retrieve it from device-tree instead. > > > > And besides, this patch fixes the memory error when running > > on top of Xen hypervisor: > > > > (XEN) traps.c:1999:d0v0 HSR=0x93830007 pc=0xc0b097f8 gva=0xf0805000 > > gpa=0x000000e6080000 > > > > Which shows that VCPU0 in Dom0 is trying to access an address in memory > > it is not allowed to access (0x000000e6080000). > > Put simply, Xen doesn't know that it is a device's register memory > > since it wasn't described in a host device tree (which Xen parses) > > and as the result this memory region wasn't assigned to Dom0 at > > domain creation time. > > > > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshche...@epam.com> > > > > --- > > > > This patch is meant to get feedback from the community before > > proceeding further. If we decide to go this direction, all Gen2 > > device-trees should be updated (add memory region) before > > this patch going in. > > > > e.g. r8a7790.dtsi: > > > > ... > > timer { > > compatible = "arm,armv7-timer"; > > interrupts-extended = <&gic GIC_PPI 13 (GIC_CPU_MASK_SIMPLE(8) | > > IRQ_TYPE_LEVEL_LOW)>, > > <&gic GIC_PPI 14 (GIC_CPU_MASK_SIMPLE(8) | > > IRQ_TYPE_LEVEL_LOW)>, > > <&gic GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(8) | > > IRQ_TYPE_LEVEL_LOW)>, > > <&gic GIC_PPI 10 (GIC_CPU_MASK_SIMPLE(8) | > > IRQ_TYPE_LEVEL_LOW)>; > > + reg = <0 0xe6080000 0 0x1000>; > > This looks incorrect, the "arm,armv7-timer" bindings doesn't offer you > the possibility to specify an MMIO region. This makes sense because it > is meant to describe the Arch timer that is only access via co-processor > registers. > > Looking at the code, I think the MMIO region corresponds to the > coresight (based on the register name). So you may want to describe the > coresight in the Device-Tree.
This is the "counter module", not the ARM v7 timer, cfr. Mark Rutland's response in an earlier discussion about describing this in DT in "Re: Architecture Timer on R-Car Gen2" https://lore.kernel.org/linux-renesas-soc/20170705113335.GE25115@leverpostej/ Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds