Package: src:xen Version: 4.11.1~pre.20180911.5acdd26fdc+dfsg-1~exp1 HP Proliant servers feature a virtual serial port which can be accessed by setting up an ssh session to the management interface (ilo) and then doing vsp:
---- >8 ---- -$ ssh luser@box-ilo luser@box-ilo's password: User:luser logged-in to box-ilo iLO Advanced 2.61 at Jul 27 2018 Server Name: box (CZXXXXXXXX) Server Power: On </>hpiLO-> vsp Virtual Serial Port Active: COM2 Starting virtual serial port. Press 'ESC (' to return to the CLI Session. Debian GNU/Linux 9 box hvc0 box login: ---- >8 ---- Now, if I e.g. use this... xen command line: [...] com2=115200,8n1 console=com2,vga linux command line: [...] console=tty0 console=hvc0 ...then I can access all xen and linux serial console functionality remotely. However, during boot, there's a chance (it feels like ~40% chance) that while booting Xen, this serial console gets stuck. When it does it's *always* at exactly the same point, which is right after "Brought up " So, console output is for example: ---- >8 ---- [...] (XEN) - Virtual Interrupt Delivery (XEN) - Posted Interrupt Processing (XEN) - VMCS shadowing (XEN) - VM Functions (XEN) HVM: ASIDs enabled. (XEN) HVM: VMX enabled (XEN) HVM: Hardware Assisted Paging (HAP) detected (XEN) HVM: HAP page sizes: 4kB, 2MB, 1GB (XEN) Brought up ---- >8 ---- And then it hangs. Input is also not echoed back. When doing a reboot of the server again, the queued output starts appearing during shutdown, but quickly gets killed off when the hardware reboots and the screen empties. ---- >8 ---- 20 CPUs (XEN) Dom0 has maximum 840 PIRQs (XEN) Xen kernel: 64-bit, lsb, compat32 (XEN) Dom0 kernel: 64-bit, PAE, lsb, paddr 0x1000000 -> 0x266a000 (XEN) PHYSICAL MEMORY ARRANGEMENT: (XEN) Dom0 alloc.: 000000480c000000->0000004810000000 (1025803 pages to be allocated) (XEN) Init. ramdisk: 000000487e70b000->000000487ffff4af (XEN) VIRTUAL MEMORY ARRANGEMENT: (XEN) Loaded kernel: ffffffff81000000->ffffffff8266a000 (XEN) Init. ramdisk: 0000000000000000->0000000000000000 (XEN) Phys-Mach map: 0000008000000000->0000008000800000 (XEN) Start info: ffffffff8266a000->ffffffff8266a4b4 (XEN) Xenstore ring: 0000000000000000->0000000000000000 (XEN) Console ring: 0000000000000000->0000000000000000 (XEN) Page tables: ffffffff8266b000->ffffffff82682000 (XEN) Boot stack: ffffffff82682000->ffffffff82683000 (XEN) TOTAL: ffffffff80000000->ffffffff82800000 (XEN) ENTRY ADDRESS: ffffffff82433180 (XEN) Dom0 has maximum 4 VCPUs [...] ---- >8 ---- I've seen this happen on all HP Proliant dl360 gear we have, g7, gen8 and gen9 (and we only have dl360). I think I first saw it with Xen 4.4 in Jessie long ago, but my memory may be failing, and it might as well also have happened with 4.1 in Wheezy already. Since I want a working serial console (the alternative is some windows program to show the VGA, in which I can't copy paste etc), currently we always check the vsp after a reboot and reboot again until it doesn't hang. This is obviously a big annoyance and waste of time. I'd like to find out if this is a bug in Xen, or if not, if it can be worked around. It feels like some kind of race condition thing. -- Hans van Kranenburg