Differential D10581
Raise BLOCKIF_IOV_MAX to 128. Windows uses at least 67 and qemu alsosupports 128. Authored by araujo on May 3 2017, 7:09 AM. Tags None Referenced Files
Details A Windows 10 vm using virtio-blk throws the following error: It was dicussed here[1] already, but Jakub didn't upstream the patch for review I guess. [1] http://freebsd.1045724.x6.nabble.com/pci-virtio-block-c-Assertion-failed-line-216-td6155786.html
Diff Detail
Event TimelineComment Actions When this languished I suspected there was more than meets the eye, but I thought about it can't figure it out. Just curious -- or will it be obvious from the reworked diff -- why didn't this work? Comment Actions Yes, I got @grehan email with some changes that I'm still investigating. But I got another problem to run Windows 2016 Server on one of my machines, so I got distracted with that. I will come back to this patch soon. Thanks guys, Comment Actions Side band communications are not very helpful, that email should of been attached to this review, or at least a note that there was a side band issue raised would of saved a few man cycles. Comment Actions There was already a review for this in D9033 where I pointed out the initial fix by myself that bumped the number of descs, and the subsequent backout when it broke Linux guests :( IOV_MAX is used in a couple of places that aren't related to this change. The usage in pci_ahci.c should be changed to just 33, as in the previous commit, since that's all that is needed there, with a CTASSERT to make sure IOV_MAX is >= 33. The problematic one is in pci_virtio_block.c where the maximum segs is reported to the guest. When IOV_MAX is > VTBLK_RINGSZ, it looked like some older Linux virtio code would end up attempting to queue up max-segs worth of data inline (and not use indirect descriptors) resulting in a crash. Naturally, my latest attempt to fix this worked fine on Win10 but broke on Linux :( Still working on it. |