Where exactly can I find in the Linux kernel code the limit set for MSI and MSI-X supporting 32 vectors and 2048 vectors respectively ?
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Where exactly can I find in the Linux kernel code the limit set for MSI and MSI-X supporting 32 vectors and 2048 vectors respectively ?
The limits to which you are referring are actually from the PCI standard. See, for example, this freely available briefing on MSI:
http://www.pcisig.com/developers/main/training_materials/get_document?doc_id=1c17cc8e96e3c1969ef8969569648e10d65d7e4d
In the kernel itself, there’s some sanity checking in the MSI source code, but it looks like the maximum number of vectors is pulled from the PCI config space of the device, which should never return more than 32 (2048):
http://lxr.free-electrons.com/source/drivers/pci/msi.c?a=sh#L811