Re: [RFC PATCH v3 02/19] scripts: bug fixes in update-aarch64-cpu-sysreg-properties

> On 14 Aug 2026, at 7:15 PM, Eric Auger <[email protected]> wrote:
> 
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> 
> On 8/3/26 4:32 PM, Khushit Shah wrote:
>> 
>>> On 20 Jul 2026, at 7:54 PM, Eric Auger <[email protected]> wrote:
>>> 
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>>> CAUTION: External Email
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>>> 
>>> On 7/16/26 11:38 PM, Khushit Shah wrote:
>>>> - handle quoted bitstrings  and decimal
>>>> - skip Values.ValueRange entries.
>>> The above is the issue you reported on my v6. See my comment on the
>>> other thread.
>> Acked.
>>>> - Emit unique RESx_{lsb} names for reserved fields so no two fields in
>>>> a register share a name.
>>> The requirement for naming RES field needs to be explained. I understand
>>> that now you expose all fields including those which are not writable it
>>> may be required but at this stage I still fail why this is requested.
>> I think we don’t need to expose RES fields to users. 
>> I was thinking of case where a RES0 field is repurposed for
>> something else, but that should be taken care by zeroing the
>> ID regs array before initiating the named model hierarchy.
>> (RES1 field in CTR_EL0 needs some handling).
> I also think so. you can rely on AARCHMRS desc to identify the right
> default values.
Acked.

>> 
>> On why we even need to expose non-writable fields:
>> - Assume some non-writable field mismatches for the model and
>>  host, why do we want to stop users from explicitly overriding
>>  the model's field value to host value?
> 
> I agree this needs to be checked. However as I suggested I think you can
> avoid exposing them to the end-users as props. You just need to read the
> value from host and compare it with the value set in the named model. 
I am not sure how that will work, assume following scenario:

- Host is running on `neoverse-v2` core and we want to run guest with `neoverse-v1`
  model. “pauth” fields are not exactly writable, and "neoverse-v1” implements
  different pauth algorithm than "neoverse-v2”. Now, if we don’t expose “pauth” as
  it is not writable, how will end user be able to say I want to run neoverse-v1
  model so please disable "pauth”.

What I want to support is end user to say "please use the host value for some non-writable
fields as the model I want to run has values which are not supported on the current host.”

The same “pauth” example will suffer if we don’t expose APA/GPA in cpu-model-expansion,
how will management stack infer that both host supports “pauth" but they support different
versions and are not compatible?

Warm Regards,
Khushit

>> 
>> 
>>>> - Emit a dummy 64-bit VAL field for registers with no defined fields,
>>>> such as AIDR_EL1 and REVIDR_EL1.
>>> This is yet another functional change that could be separate.
>> Acked, will do in v4.
> 
> Thanks
> 
> Eric
>> 
>>> Thanks
>>> 
>>> Eric
>>>> Signed-off-by: Khushit Shah <[email protected]>
>>>> ---
>>>> .../update-aarch64-cpu-sysreg-properties.py   | 67 +++++++++++++------
>>>> 1 file changed, 45 insertions(+), 22 deletions(-)
>>>> mode change 100644 => 100755 scripts/update-aarch64-cpu-sysreg-properties.py
>>>> 
>>>> diff --git a/scripts/update-aarch64-cpu-sysreg-properties.py b/scripts/update-aarch64-cpu-sysreg-properties.py
>>>> old mode 100644
>>>> new mode 100755
>>>> index 9e829fda2e..ecc35db528
>>>> --- a/scripts/update-aarch64-cpu-sysreg-properties.py
>>>> +++ b/scripts/update-aarch64-cpu-sysreg-properties.py
>>>> @@ -106,6 +106,29 @@ def collect_fields(item, bit_offset=0):
>>>> 
>>>>    return fields
>>>> 
>>>> +def parse_value_int(raw_val):
>>>> +    if raw_val is None or isinstance(raw_val, bool):
>>>> +        return None
>>>> +
>>>> +    # may already be real number
>>>> +    if isinstance(raw_val, int):
>>>> +        return raw_val
>>>> +
>>>> +    raw_str = str(raw_val).strip()
>>>> +
>>>> +    if "'" in raw_str:
>>>> +        # quoted bitstring like "'0100'"
>>>> +        bits = raw_str.replace("'", "")
>>>> +        try:
>>>> +            return int(bits, 2)
>>>> +        except ValueError:
>>>> +            return None
>>>> +
>>>> +    # unquoted, try decimal
>>>> +    try:
>>>> +        return int(raw_str, 0)
>>>> +    except ValueError:
>>>> +        return None
>>>> 
>>>> def extract_field_enums(field):
>>>>    enums = []
>>>> @@ -124,32 +147,23 @@ def extract_field_enums(field):
>>>>    if not isinstance(val_entries, list):
>>>>        return enums
>>>> 
>>>> +    # A Values.ValueRange field specifies start and end value for a range.
>>>> +    # Don't enumerate anything for them.
>>>> +    for val_entry in val_entries:
>>>> +        if isinstance(val_entry, dict) and \
>>>> +           val_entry.get("_type") == "Values.ValueRange":
>>>> +               return []
>>>> +
>>>>    for val_entry in val_entries:
>>>>        if not isinstance(val_entry, dict):
>>>>            continue
>>>> -            
>>>> +
>>>>        if val_entry.get("_type") == "Values.Value":
>>>> -            raw_val = val_entry.get("value")
>>>> -            if raw_val is None:
>>>> +            int_val = parse_value_int(val_entry.get("value"))
>>>> +            if int_val is None:
>>>>                continue
>>>> -                
>>>> -            # some of the values have ' like "'0100'"
>>>> -            raw_val_str = str(raw_val).strip().replace("'", "")
>>>> -            
>>>> -            try:
>>>> -                # convert into bin 
>>>> -                int_val = int(raw_val_str, 2)
>>>> -            except ValueError:
>>>> -                try:
>>>> -                    # Fallback to dec if not bin
>>>> -                    int_val = int(raw_val_str, 0)
>>>> -                except ValueError:
>>>> -                    continue
>>>> -            
>>>> -            enums.append({
>>>> -                'value': int_val
>>>> -            })
>>>> -            
>>>> +            enums.append({'value': int_val})
>>>> +
>>>>    return enums
>>>> 
>>>> def generate_sysreg_properties_from_registers_json(id_reg_names, raw_json_path):
>>>> @@ -210,7 +224,7 @@ def generate_sysreg_properties_from_registers_json(id_reg_names, raw_json_path):
>>>>                       msb > current_fieldset_fields[unique_key]['msb']:
>>>>                        enums = extract_field_enums(val)
>>>>                        current_fieldset_fields[unique_key] = {
>>>> -                            'raw_name': name,
>>>> +                            'raw_name': unique_key,
>>>>                            'lsb': lsb,
>>>>                            'msb': msb,
>>>>                            'width': width,
>>>> @@ -238,6 +252,15 @@ def generate_sysreg_properties_from_registers_json(id_reg_names, raw_json_path):
>>>>        # Sort decreasing lsbs
>>>>        sorted_fields = sorted(unique_fields.items(),
>>>>                               key=lambda x: x[1]['lsb'], reverse=True)
>>>> +        if len(sorted_fields) == 0:
>>>> +            # cases like REVIDR_EL1 and AIDR_EL1.
>>>> +            # augment a dummy fields VAL.
>>>> +            sorted_fields.append(('VAL', {
>>>> +                'lsb': 0,
>>>> +                'msb': 63,
>>>> +                'width': 64,
>>>> +                'enums': []
>>>> +            }))
>>>> 
>>>>        for unique_key, bits in sorted_fields:
>>>>            enums_list = bits.get('enums', [])