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    /dev/xvda not appearing in guest

    Scheduled Pinned Locked Moved Compute
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    • olivierlambertO Offline
      olivierlambert Vates 🪐 Co-Founder CEO
      last edited by olivierlambert

      This information is available in Xen Orchestra (current VM virt mode)

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      • R Offline
        r1 XCP-ng Team @keeely
        last edited by

        @keeely said in /dev/xvda not appearing in guest:

        I had to compile in support for rtl8139 C+ to get networking to work because the usual rtl 8139 driver did not work.

        Is this for Host or VM?

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        • K Offline
          keeely @olivierlambert
          last edited by

          That was for VM.

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          • K Offline
            keeely @olivierlambert
            last edited by

            @olivierlambert I found only this under advanced:

            f7eb4f1b-7c04-4d31-aa58-6d5d390c47b6-image.png

            Also under general section for the VM:

            93ede9ad-b089-43fa-ba0b-5774633efc29-image.png

            So what does that mean? HVM? If so where is the PVHVM option?

            Interestingly under disks, I see this:

            69614458-39a0-42e8-b7e1-ecd885fa3c57-image.png

            So the device is listed as xvda, however dmesg in the guest shows sda has been detected.

            62a2fba1-a229-4ea4-b508-1b4714be6748-image.png

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            • K Offline
              keeely @keeely
              last edited by

              @keeely Looking at the XOA appliance, it does seem to have the right mode:

              a88b6518-ff45-4b90-823c-45fad63ca8fd-image.png

              Shame there is no /proc/config.gz on that VM so I can lift the kernel config.

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              • olivierlambertO Offline
                olivierlambert Vates 🪐 Co-Founder CEO
                last edited by

                So it means there's no emulated PV drivers installed (or they aren't loaded) 😕

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                • R Offline
                  r1 XCP-ng Team
                  last edited by

                  Can you try and compile it with "M" and push them in initrd?

                  Without PV drivers (Pure emulation mode) it generally detects as /dev/hda, seems it can also do /dev/sda.

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                  • K Offline
                    keeely @r1
                    last edited by

                    @r1 said in /dev/xvda not appearing in guest:

                    Can you try and compile it with "M" and push them in initrd?

                    I have been avoiding this due to the insane amount of time it takes to do the full module compile using nested virtualisation (Slackware under XCP-ng under VMWare Fusion). But assuming that I do do it, why do I need initrd? Can't I just boot using /dev/sda1, and load the vbd frontend driver after boot? Won't both those devices still be present?

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                    • R Offline
                      r1 XCP-ng Team @keeely
                      last edited by

                      @keeely Once the disk is opened by a program (emulated driver), and OS runs from it, I don't think it will allow Xen blkdev to take over. Thus the new module would render useless.

                      By putting in initrd, the kernel will load it at boot time and then disk is opened to continue boot.

                      CONFIG_XEN_BLKDEV_FRONTEND=y should have worked too but I guess that's another troubleshooting.

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                      • K Offline
                        keeely @r1
                        last edited by

                        @r1 That's very useful info. I will try to make initrd.

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                        • K Offline
                          keeely @keeely
                          last edited by

                          There is no need to use initrd, and I finally have this booting with kernel 4.4.14 and optimised IO.

                          Here are the kernel options I used:

                          # cat .config | grep XEN
                          CONFIG_XEN=y
                          CONFIG_XEN_DOM0=y
                          CONFIG_XEN_PVHVM=y
                          CONFIG_XEN_512GB=y
                          CONFIG_XEN_SAVE_RESTORE=y
                          # CONFIG_XEN_DEBUG_FS is not set
                          # CONFIG_XEN_PVH is not set
                          CONFIG_PCI_XEN=y
                          CONFIG_XEN_PCIDEV_FRONTEND=y
                          CONFIG_XEN_BLKDEV_FRONTEND=y
                          # CONFIG_XEN_BLKDEV_BACKEND is not set
                          CONFIG_XEN_SCSI_FRONTEND=y
                          CONFIG_NETXEN_NIC=m
                          CONFIG_XEN_NETDEV_FRONTEND=y
                          # CONFIG_XEN_NETDEV_BACKEND is not set
                          CONFIG_INPUT_XEN_KBDDEV_FRONTEND=y
                          CONFIG_HVC_XEN=y
                          CONFIG_HVC_XEN_FRONTEND=y
                          # CONFIG_TCG_XEN is not set
                          # CONFIG_XEN_WDT is not set
                          CONFIG_XEN_FBDEV_FRONTEND=y
                          CONFIG_XEN_BALLOON=y
                          # CONFIG_XEN_BALLOON_MEMORY_HOTPLUG is not set
                          CONFIG_XEN_SCRUB_PAGES=y
                          CONFIG_XEN_DEV_EVTCHN=y
                          CONFIG_XEN_BACKEND=y
                          CONFIG_XENFS=y
                          CONFIG_XEN_COMPAT_XENFS=y
                          CONFIG_XEN_SYS_HYPERVISOR=y
                          CONFIG_XEN_XENBUS_FRONTEND=y
                          CONFIG_XEN_GNTDEV=m
                          CONFIG_XEN_GRANT_DEV_ALLOC=m
                          CONFIG_SWIOTLB_XEN=y
                          CONFIG_XEN_PCIDEV_BACKEND=m
                          # CONFIG_XEN_SCSI_BACKEND is not set
                          CONFIG_XEN_PRIVCMD=y
                          CONFIG_XEN_ACPI_PROCESSOR=m
                          # CONFIG_XEN_MCE_LOG is not set
                          CONFIG_XEN_HAVE_PVMMU=y
                          CONFIG_XEN_EFI=y
                          CONFIG_XEN_AUTO_XLATE=y
                          CONFIG_XEN_ACPI=y
                          CONFIG_XEN_SYMS=y
                          CONFIG_XEN_HAVE_VPMU=y
                          

                          XCP-ng Center reports IO Optimised.
                          XOA still reports the VM as HVM.

                          I can finally see the /dev/xvda device inside the guest however.

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                          • R Offline
                            r1 XCP-ng Team
                            last edited by

                            So some issue in between 4.4.14 (why not 4.4.229?) vs 5.4.21 (or 5.4.50?).

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                            • K Offline
                              keeely @r1
                              last edited by keeely

                              @r1 I haven't done a 'make oldconfig' using the 4.4.14 kernel config, which would obviously be the next step. There's a long time-period between those two kernels unfortunately, a lot could have changed. The config options in the kernel are somewhat different.

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                              • K Offline
                                keeely
                                last edited by

                                It seems I got a kernel panic for some other reason with 5.4.21. It's all working now, thanks.

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