Re: [Qemu-devel] [PATCH RFC] Implement GIC-500 from GICv3 family for arm64

[Peter Maydell <peter.maydell@linaro.org>]

On 9 March 2015 at 23:41,  <shlomo.pongratz@toganetworks.com> wrote:
> From: Shlomo Pongratz <shlomo.pongratz@huawei.com>
>
> This patch is a first step toward 128 cores support for arm64.
>
> At first only 64 cores are supported for two reasons:
> First the largest integer type has the size of 64 bits and modifying
> essential data structures in order to support 128 cores will require
> the usage of bitops.
> Second currently the Linux (kernel) can be configured to support
> up to 64 cores thus there is no urgency with 128 cores support.
>
> Things left to do:
>
> Currently the booting Linux may got stuck. The probability of getting stuck
> increases with the number of cores. I'll appreciate core review.
>
> There is a need to support flexible clusters size. The GIC-500 can support
> up to 128 cores, up to 32 clusters and up to 8 cores is a cluster.
> So for example, if one wishes to have 16 cores, the options are:
> 2 clusters of 8 cores each, 4 clusters with 4 cores each
> Currently only the first option is supported.
> There is an issue of passing clock affinity to via the dtb. In the dtb
>
> interrupt section there are only 24 bit left to affinity since the
> variable is a 32 bit entity and 8 bits are reserved for flags.
> See Documentation/devicetree/bindings/arm/arch_timer.txt.
> Note that this issue is not seems to be critical as when checking
> /proc/irq/3/smp_affinity with 32 cores all 32 bits are one.
>
> The last issue is to add support for 128 cores. This requires the usage
> of bitops and currently can be tested up to 64 cores.
>
> Signed-off-by: Shlomo Pongratz <shlomo.pongratz@toganetworks.com>
> ---
>  hw/arm/Makefile.objs               |    2 +-
>  hw/arm/virtv2.c                    |  774 +++++++++++++++++
>  hw/intc/Makefile.objs              |    2 +
>  hw/intc/arm_gic_common.c           |    2 +
>  hw/intc/arm_gicv3.c                | 1596 ++++++++++++++++++++++++++++++++++++
>  hw/intc/arm_gicv3_common.c         |  188 +++++
>  hw/intc/gicv3_internal.h           |  153 ++++
>  include/hw/intc/arm_gicv3.h        |   44 +
>  include/hw/intc/arm_gicv3_common.h |  136 +++
>  target-arm/cpu.c                   |    1 +
>  target-arm/cpu.h                   |    6 +
>  target-arm/cpu64.c                 |   92 +++
>  target-arm/helper.c                |   12 +-
>  target-arm/psci.c                  |   18 +-
>  target-arm/translate-a64.c         |   14 +
>  15 files changed, 3034 insertions(+), 6 deletions(-)
>  create mode 100644 hw/arm/virtv2.c
>  create mode 100644 hw/intc/arm_gicv3.c
>  create mode 100644 hw/intc/arm_gicv3_common.c
>  create mode 100644 hw/intc/gicv3_internal.h
>  create mode 100644 include/hw/intc/arm_gicv3.h
>  create mode 100644 include/hw/intc/arm_gicv3_common.h

This is way too big to review as a single patch; you should
find a way to split it into a series of multiple coherent patches.

thanks
-- PMM