Re: [PATCH] hw/riscv/virt.c: re-insert and deprecate 'riscv, delegate'

[Alistair Francis]

On Sun, Jul 14, 2024 at 3:44 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> Commit b1f1e9dcfa renamed 'riscv,delegate' to 'riscv,delegation' since
> it is the correct name as per dt-bindings, and the absence of the
> correct name will result in validation fails when dumping the dtb and
> using dt-validate.
>
> But this change has a side-effect: every other firmware available that
> is AIA capable is using 'riscv,delegate', and it will fault/misbehave if
> this property isn't present. The property was added back in QEMU 7.0,
> meaning we have 2 years of firmware development using the wrong
> property.
>
> Re-introducing 'riscv,delegate' while keeping 'riscv,delegation' will
> make current firmwares to keep booting with the 'virt' machine and
> dt-validate won't complain about it since we're still using the expected
> property 'riscv,delegation'. 'riscv,delegate' is then marked for future
> deprecation and its use is being discouraged.
>
> Cc: Conor Dooley <conor@kernel.org>
> Cc: Anup Patel <apatel@ventanamicro.com>
> Fixes: b1f1e9dcfa ("hw/riscv/virt.c: aplic DT: rename prop to 'riscv, 
> delegation'")
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  docs/about/deprecated.rst | 11 +++++++++++
>  hw/riscv/virt.c           |  9 +++++++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
> index 20b7a17cf0..88f0f03786 100644
> --- a/docs/about/deprecated.rst
> +++ b/docs/about/deprecated.rst
> @@ -479,6 +479,17 @@ versions, aliases will point to newer CPU model versions
>  depending on the machine type, so management software must
>  resolve CPU model aliases before starting a virtual machine.
>
> +RISC-V "virt" board "riscv,delegate" DT property (since 9.1)
> +''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
> +
> +The "riscv,delegate" DT property was added in QEMU 7.0 as part of
> +the AIA APLIC support.  The property changed name during the review
> +process in Linux and the correct name ended up being
> +"riscv,delegation".  Changing the DT property name will break all
> +available firmwares that are using the current (wrong) name.  The
> +property is kept as is in 9.1, together with "riscv,delegation", to
> +give more time for firmware developers to change their code.
> +
>  Migration
>  ---------
>
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index bc0893e087..9981e0f6c9 100644
> --- a/hw/riscv/virt.c
> +++ b/hw/riscv/virt.c
> @@ -651,6 +651,15 @@ static void create_fdt_one_aplic(RISCVVirtState *s, int 
> socket,
>          qemu_fdt_setprop_cells(ms->fdt, aplic_name, "riscv,delegation",
>                                 aplic_child_phandle, 0x1,
>                                 VIRT_IRQCHIP_NUM_SOURCES);
> +        /*
> +         * DEPRECATED_9.1: Compat property kept temporarily
> +         * to allow old firmwares to work with AIA. Do *not*
> +         * use 'riscv,delegate' in new code: use
> +         * 'riscv,delegation' instead.
> +         */
> +        qemu_fdt_setprop_cells(ms->fdt, aplic_name, "riscv,delegate",
> +                               aplic_child_phandle, 0x1,
> +                               VIRT_IRQCHIP_NUM_SOURCES);
>      }
>
>      riscv_socket_fdt_write_id(ms, aplic_name, socket);
> --
> 2.45.2
>
>