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Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.192 and 1.193

-version 1.192, 2021/03/03 13:19:06
+version 1.193, 2021/03/03 14:22:24
  Line 167  menu=Xen:load /netbsd-XEN3_DOM0.gz conso
  menu=Xen single user:load /netbsd-XEN3_DOM0.gz console=pc -s;multiboot /xen.gz dom0_mem=512M
  """]]
- \todo Explain why console=pc is given.  Perhaps there is some notion
- of a separate console instead of xencons.
- \todo Check the single user line.
  This specifies that the dom0 should have 512MB of ram, leaving the rest
  to be allocated for domUs.
- Line 187  See boot_console(8).  Understand that yo
+ Line 182  See boot_console(8).  Understand that yo
  having console setup correct for booting GENERIC before trying to
  configure Xen.
- By default, the hypervisor (Xen itself) will use \todo as the console
+ Generally for GENERIC, one sets the console in bootxx_ffsv1 or
+ equivalent, and this is passed on to /boot (where one typically does
- By default, the NetBSD dom0 kernel will use xencons(4) (the man page
+ not set the console).  This configuration of bootxx_ffsv1 should also
- does not exist) as console.
+ be in place for Xen systems, to allow seeing messages from /boot and
+ use of a keyboard to select a line from the menu.  And, one should
- To use a serial console for the Xen hypervisor, add settings as follows:
+ have a working boot path to GENERIC for rescue situations.
+ With GENERIC, the boot options are passed on to /netbsd, but there is
+ currently no mechanism to pass these via multiboot to the hypervisor.
+ Thus, in addition to configuring the console in the boot blocks, one
+ must also configure it for Xen.
+ By default, the hypervisor (Xen itself) will use some sort of vga
+ device as the console, much like GENERIC uses by default.  The vga
+ console is relinquished at the conclusion of hypervisor boot, before
+ the dom0 is started.
+ \todo Explain if there is any notion of input to the Xen console;
+ there is something about 3 CTRL-As in a row.  Perhaps this is about
+ the serial console which is not relinquished?
+ The hypervisor can be configured to use a serial port console, e.g.
  [[!template id=filecontent name="/boot.cfg" text="""
- menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
+ menu=Xen:losad /netbsd-XEN3_DOM0.gz console=com0;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
  """]]
+ This exampulee uses the first serial port (Xen counts from 1; this is
- which will use the first serial port for Xen (which counts starting
+ what NetBSD would call com0), and sets speed and parity.  (The dom0 is
- from 1, unlike NetBSD which counts starting from 0), forcing
+ then configured to use the same serial port in this example.)
- speed/parity.  Because the NetBSD command line lacks a
- "console=pc" argument, it will use the default "xencons" console device,
+ One also configures the console for the dom0.  While one might expect
- which directs the console I/O through Xen to the same console device Xen
+ console=pc to be default, following behavior of GENERIC, a hasty read
- itself uses (in this case, the serial port).
+ of the code suggests there is no default and booting without a
+ selected console might lead to a panic.  Also, there is merit in
- \todo Explain why boot.cfg shows forcing the dom0 console also,
+ explicit configuration.  Therefore the standard approach is to place
- separately from the hypervisor console.
+ console=pc as part of the load statement for the dom0 kernel, or
+ alternatively console=com0.
+ The NetBSD dom0 kernel will attach xencons(4) (the man page does not
+ exist), but this is not used as a console.  It is used to obtain the
+ messages from the hypervisor's console; run `xl dmesg` to see them.
  ### Tuning

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