On 04/04/2019 19:19, Jan Kiszka wrote: > On 04.04.19 19:02, Andrej Utz wrote: >> Hello everyone, >> >> after recompiling the kernel (minor changes), I noticed a big >> reduction of mmio regions after regenerating the root cell config with >> critical hardware like AHCI within. Turned out a big chunk of iomem >> regions went a level deeper in the tree with "Reserved" as its parent >> node (see appendix for more). I'm not sure yet, but I think enabling >> AMD IOMMU v2 resulted in this. > > You should see a different result then when disabling it on the command > line (amd_iommu=off).
Sorry for not mentioning, but amd_iommu is always "off". >> From reading sysfs_parser.py:905 I gathered that "Reserved" region >> nodes are, with exception of HPET, completely ignored. In my case the >> whole PCI bus goes missing so I'd like to know the rationale behind this. > > Well, the kernel used to report regions as "reserved" that were actually > reserved to it during runtime, thus won't be touched anymore. > Apparently, this definition changed. It would be good to under stand a > pattern, but the simplest workaround for now would be either including > reserved regions again (though we need to see if this doesn't overshoot) > or making this at least configurable (--with-reserved-regions or so). After booting the mainline kernel and still having that reserved region in iomem I'm pretty sure the BIOS update I did earlier is responsible. Somewhat strange is that this kind of region is reserved on other systems too (delayed change from 'usable' by e820 in early boot), but Linux doesn't show it in iomem there. Keeping that in mind the "--with-reserved-regions" option fits perfectly for such shenanigans. I will test a bit more over weekend and probably write a patch for it. Thanks, Andrej Utz -- 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 jailhouse-dev+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
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