Package: kdump-tools Version: 1:1.6.10 When the "ata_piix.prefer_ms_hyperv=0" parameter is present, the kdump kernel uses the legacy ata_piix IDE driver rather than the hv_storvsc driver to access the disk. Some Hyper-V hosts do not work with the ata_piix driver and the VM is unable to write out the vmcore.
"ata_piix.prefer_ms_hyperv=0" was originally added in Oct 2016 (https://salsa.debian.org/debian/kdump-tools/-/commit/4e7997bcd953a9c2a1c473fb20a549d3db8cae44): at that time this kernel parameter was needed to work around a kdump issue with old Linux kernels on old Hyper-V (e.g. Windows Server 2012 R2): see https://docs.microsoft.com/en-US/troubleshoot/windows-client/virtualization/cant-use-kdump-kexec-linux-virtual-machines-hyper-v. Proposed solution: The string "ata_piix.prefer_ms_hyperv=0" should be removed from debian/rules. Thanks, Kellen -- Kellen Renshaw Associate Software Engineer (SEG) Canonical Ltd. kellen.rens...@canonical.com www.canonical.com | www.ubuntu.com