Hi all,

I install Xen 4.8 on Ubuntu 17.04 (kernel is updated to 4.12). But I found only 1 CPU was detected.

I thought it is caused by some BIOS settings, so I enabled x2APIC in BIOS, unfortunately, Linux hangs during booting after printing "Loading initial ramdisk ...".

I have to disable x2APIC finally, but I only have 1 CPU when system is up. Does anyone encounter this issue?

The whole dmesg was attached. Xen related output.

[    0.000000] Xen: [mem 0x0000000000000000-0x000000000009ffff] usable
[    0.000000] Xen: [mem 0x00000000000a0000-0x00000000000fffff] reserved
[    0.000000] Xen: [mem 0x0000000000100000-0x000000007a088fff] usable
[    0.000000] Xen: [mem 0x000000007a089000-0x000000007a188fff] reserved
[    0.000000] Xen: [mem 0x000000007a189000-0x000000007a288fff] type 20
[    0.000000] Xen: [mem 0x000000007a289000-0x000000007af0afff] reserved
[    0.000000] Xen: [mem 0x000000007af0b000-0x000000007b93afff] ACPI NVS
[    0.000000] Xen: [mem 0x000000007b93b000-0x000000007bab4fff] ACPI data
[    0.000000] Xen: [mem 0x000000007bab5000-0x000000007bae8fff] usable
[    0.000000] Xen: [mem 0x000000007bae9000-0x000000007bafefff] ACPI data
[    0.000000] Xen: [mem 0x000000007baff000-0x000000007bafffff] usable
[    0.000000] Xen: [mem 0x0000000080000000-0x000000008fffffff] reserved
[    0.000000] Xen: [mem 0x00000000feda8000-0x00000000fedabfff] reserved
[    0.000000] Xen: [mem 0x00000000fee00000-0x00000000feefffff] reserved
[    0.000000] Xen: [mem 0x00000000ff310000-0x00000000ffffffff] reserved
[    0.000000] Xen: [mem 0x0000000100000000-0x000000187fffffff] usable
[    0.000000] Hypervisor detected: Xen PV
[    0.000000] Booting paravirtualized kernel on Xen
[    0.000000] Xen version: 4.8.0 (preserve-AD)
[    0.000000] xen: PV spinlocks enabled
[    0.004000] xen:events: Using FIFO-based ABI
[    0.004000] clocksource: xen: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
[    0.004000] Xen: using vcpuop timer interface
[    0.004000] installing Xen timer for CPU 0
[    0.103141] xen:grant_table: Grant tables using version 1 layout
[    0.105359] xen:balloon: Initialising balloon driver
[    0.118198] xen_balloon: Initialising balloon driver
[    0.169556] clocksource: Switched to clocksource xen
[    0.914651]  xen_acpi_processor_init+0x5f/0x1f6
[    0.965809] xen_netfront: Initialising Xen virtual ethernet driver
[    2.011142] genirq: Flags mismatch irq 8. 00000080 (rtc0) vs. 00000000 (xen-pcpu)
[    6.722743] systemd[1]: Detected virtualization xen.
[   21.072897] xen:xen_evtchn: Event-channel device installed
[   21.204752] xen:manage: Unable to read sysrq code in control/sysrq

Thanks
Hongjiang Zhang