[Skiboot] [PATCH v8 20/24] MPIPL: Add OPAL API to query saved tags

Hari Bathini hbathini at linux.ibm.com
Wed Jul 10 20:50:52 AEST 2019

On 10/07/19 3:05 PM, Oliver O'Halloran wrote:
> On Wed, Jul 10, 2019 at 5:11 PM Hari Bathini <hbathini at linux.ibm.com> wrote:
>> Sorry, if I was not clear but that is how it is. Metadata is setup by
>> production kernel based on user configuration and after crash, petitboot kernel
>> looks for this metadata to work out how much memory it is allowed to trash
>> (https://patchwork.ozlabs.org/patch/1122300/).
>> As for the type field in the metadata, that requirement comes from the need to
>> keep metadata retrieval simple. Without a type field, we need to have a predefined
>> ordering or kernel has to remember which tag no. corresponds to which data type.
>> While the former seems naive, the later, brings with it a need to handle kernel
>> metadata separately as we need to get that data before processing tags.
> I don't see a problem with either approach. Say we do the "naive"
> thing and change the API to this:
> enum opal_mpipl_tag {
> }
> And fetch the tags with:
> int64_t opal_mpipl_query_tag(enum opal_mpipl_tag tag, uint64_t *tag_value);

Actually, I would love to have it this way but I remember Nick was not for having a
type field in the opal call..


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