On 2016-06-23 13:47, Valentine Sinitsyn wrote: > On 23.06.2016 14:35, Jan Kiszka wrote: >> On 2016-06-23 13:28, Valentine Sinitsyn wrote: >>> Hi Jan, >>> >>> On 23.06.2016 13:53, Jan Kiszka wrote: >>>> On 2016-06-23 11:33, Valentine Sinitsyn wrote: >>>>> Hi all, >>>>> >>>>> What is the semantics of system_config->interrupt_limit field? >>>>> >>>>> Am I right that this is a maximum number of distinct interrupt >>>>> messages >>>>> a board is allowed to generate? Or is it an architectural limit for >>>>> the >>>>> number of vectors? >>>> >>>> In practice, it is the maximum number of distinct interrupt sources to >>>> expect on Intel systems, used to size the IR table appropriately (on >>>> AMD, they are device-bound, so you shouldn't have a need for this). As >>>> we have no SMMU for ARM yet, I'm not sure if there will be a reuse. If >>>> not, we can make it x86-only. >>> I'm inclined to have a single shared interrupt table on AMD as well. We >>> don't have a subpage allocator in Jailhouse (I've sketched one last >>> night, but it didn't go really well), and handing off page-sized tables >>> to devices needing only a single IRTE seems to be a waste. So knowing >>> the size of the table in advance is also convenient. >> >> Ah, you have per-device table references, but they could point to a >> single table. Then the limit would be relevant for AMD as well. >> >> But how would you identify / filter the sources then? In contrast to >> VT-d IRTEs, you do not seem to have source ID matching with AMD IRTEs, >> do you? > That's true. I think I'll store a reverse mapping from bdf to the offset > within single table, much like amd_iommu driver does in the Linux kernel.
So you will have one forward table per cell in order to achieve partitioning? That may work... In Intel, there is a single table for them all, and source matching is used for partitioning. Jan -- Siemens AG, Corporate Technology, CT RDA ITP SES-DE Corporate Competence Center Embedded Linux -- You received this message because you are subscribed to the Google Groups "Jailhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
