[PATCH v2 0/5] kdump: crashkernel reservation from CMA

[David Hildenbrand]

On 30.05.25 11:07, Michal Hocko wrote:
> On Fri 30-05-25 10:39:39, David Hildenbrand wrote:
>> On 30.05.25 10:28, Michal Hocko wrote:
> [...]
>>> All that being said I would go with an additional parameter to the
>>> kdump cma setup - e.g. cma_sane_dma that would skip waiting and use 10s
>>> otherwise. That would make the optimized behavior opt in, we do not need
>>> to support all sorts of timeouts and also learn if this is not
>>> sufficient.
>>>
>>> Makes sense?
>>
>> Just so I understand correctly, you mean extending the "crashkernel=" option
>> with a boolean parameter? If set, e.g., wait 1s, otherwise magic number 10?
> 
> crashkernel=1G,cma,cma_sane_dma # no wait on transition

But is no wait ok? I mean, any O_DIRECT with any device would at least 
take a bit, no?

Of course, there is a short time between the crash and actually 
triggerying kdump.

> crashkernel=1G,cma # wait on transition with e.g. 10s timeout

In general, would work for me.

-- 
Cheers,

David / dhildenb