Message-ID: <CAL_Jsq+_G4wBR7tm+DvN-yYSaoAX6OgxHa0AToJYucDdhD=Dtg@mail.gmail.com>
Date:   Wed, 28 Jun 2023 17:17:13 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Pavan Kondeti <quic_pkondeti@...cinc.com>
Cc:     Mukesh Ojha <quic_mojha@...cinc.com>, corbet@....net,
        agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        keescook@...omium.org, tony.luck@...el.com, gpiccoli@...lia.com,
        mathieu.poirier@...aro.org, catalin.marinas@....com,
        will@...nel.org, linus.walleij@...aro.org,
        andy.shevchenko@...il.com, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-hardening@...r.kernel.org,
        linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-gpio@...r.kernel.org
Subject: Re: [PATCH v4 08/21] dt-bindings: reserved-memory: Add qcom,ramoops binding

On Wed, Jun 28, 2023 at 8:11 AM Pavan Kondeti <quic_pkondeti@...cinc.com> wrote:
>
> On Wed, Jun 28, 2023 at 06:04:35PM +0530, Mukesh Ojha wrote:
> > Qualcomm ramoops minidump logger provide a means of storing
> > the ramoops data to some dynamically reserved memory instead
> > of traditionally implemented ramoops where the region should
> > be statically fixed ram region. Its device tree binding
> > would be exactly same as ramoops device tree binding and is
> > going to contain traditional ramoops frontend data and this
> > content will be collected via Qualcomm minidump infrastructure
> > provided from the boot firmware.
> >
> > Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
> > ---
> >  .../devicetree/bindings/soc/qcom/qcom,ramoops.yaml | 126 +++++++++++++++++++++
> >  1 file changed, 126 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom,ramoops.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,ramoops.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom,ramoops.yaml
> > new file mode 100644
> > index 000000000000..b1fdcf3f8ad4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,ramoops.yaml
> > @@ -0,0 +1,126 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: "http://devicetree.org/schemas/soc/qcom/qcom,ramoops.yaml#"
> > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> > +
> > +title: Qualcomm Ramoops minidump logger
> > +
> > +description: |
> > +  Qualcomm ramoops minidump logger provide a means of storing the ramoops
> > +  data to some dynamically reserved memory instead of traditionally
> > +  implemented ramoops where the region should be statically fixed ram
> > +  region. Because of its similarity with ramoops it will also have same
> > +  set of property what ramoops have it in its schema and is going to
> > +  contain traditional ramoops frontend data and this region will be
> > +  collected via Qualcomm minidump infrastructure provided from the
> > +  boot firmware.
> > +
> > +maintainers:
> > +  - Mukesh Ojha <quic_mojha@...cinc.com>
> > +
> > +properties:
> > +  compatible:
> > +    items:
> > +      - enum:
> > +          - qcom,sm8450-ramoops
> > +      - const: qcom,ramoops
> > +
> > +  memory-region:
> > +    maxItems: 1
> > +    description: handle to memory reservation for qcom,ramoops region.
> > +
> > +  ecc-size:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: enables ECC support and specifies ECC buffer size in bytes
> > +    default: 0 # no ECC
> > +
> > +  record-size:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: maximum size in bytes of each kmsg dump
> > +    default: 0
> > +
> > +  console-size:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: size in bytes of log buffer reserved for kernel messages
> > +    default: 0
> > +
> > +  ftrace-size:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: size in bytes of log buffer reserved for function tracing and profiling
> > +    default: 0
> > +
> > +  pmsg-size:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: size in bytes of log buffer reserved for userspace messages
> > +    default: 0
> > +
> > +  mem-type:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: if present, sets the type of mapping is to be used to map the reserved region.
> > +    default: 0
> > +    oneOf:
> > +      - const: 0
> > +        description: write-combined
> > +      - const: 1
> > +        description: unbuffered
> > +      - const: 2
> > +        description: cached
> > +
> > +  max-reason:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    default: 2 # log oopses and panics
> > +    maximum: 0x7fffffff
> > +    description: |
> > +      If present, sets maximum type of kmsg dump reasons to store.
> > +      This can be set to INT_MAX to store all kmsg dumps.
> > +      See include/linux/kmsg_dump.h KMSG_DUMP_* for other kmsg dump reason values.
> > +      Setting this to 0 (KMSG_DUMP_UNDEF), means the reason filtering will be
> > +      controlled by the printk.always_kmsg_dump boot param.
> > +      If unset, it will be 2 (KMSG_DUMP_OOPS), otherwise 5 (KMSG_DUMP_MAX).
> > +
> > +  flags:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    default: 0
> > +    description: |
> > +      If present, pass ramoops behavioral flags
> > +      (see include/linux/pstore_ram.h RAMOOPS_FLAG_* for flag values).
> > +
> > +  no-dump-oops:
> > +    deprecated: true
> > +    type: boolean
> > +    description: |
> > +      Use max_reason instead. If present, and max_reason is not specified,
> > +      it is equivalent to max_reason = 1 (KMSG_DUMP_PANIC).
> > +
> > +  unbuffered:
> > +    deprecated: true
> > +    type: boolean
> > +    description: |
> > +      Use mem_type instead. If present, and mem_type is not specified,
> > +      it is equivalent to mem_type = 1 and uses unbuffered mappings to map
> > +      the reserved region (defaults to buffered mappings mem_type = 0).
> > +      If both are specified -- "mem_type" overrides "unbuffered".
> > +
>
> Most of the properties you added here are already documented at
> Documentation/devicetree/bindings/reserved-memory/ramoops.yaml

That is certainly a problem. Don't define the same property more than
once. Not yet checked and enforced by the tools, but it will be.

> Can't we just reference them here? would something like work?
>
> max-reason:
>   $ref: "../../reserved-memory/ramoops.yaml#/properties/max-reason

Can work, but no. Common properties need to go into a schema of common
properties which the device specific schemas reference.

>
> > +unevaluatedProperties: false
> > +
>
> will there be any additional properties be added dynamically? if not,
> should not we use "additionalProperties: false" here?

I don't know what you mean by dynamically, but that's not the criteria
for which to use.

Rob

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