docs: Add a note about mixing bootindex with "-boot order"

Occasionally the users try to mix the bootindex properties with the
"-boot order" parameter - and this likely does not give the expected
results. So let's add a proper statement that these two concepts
should not be used together.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1488303601-23741-1-git-send-email-thuth@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Thomas Huth 2017-02-28 18:40:01 +01:00 committed by Paolo Bonzini
parent e8f5fe2de1
commit c0d9f7d0bc
2 changed files with 13 additions and 1 deletions

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@ -41,3 +41,12 @@ has three bootable devices target1, target3, target5 connected to it,
the option ROM will have a boot method for each of them, but it is not
possible to map from boot method back to a specific target. This is a
shortcoming of the PC BIOS boot specification.
== Mixing bootindex and boot order parameters ==
Note that it does not make sense to use the bootindex property together
with the "-boot order=..." (or "-boot once=...") parameter. The guest
firmware implementations normally either support the one or the other,
but not both parameters at the same time. Mixing them will result in
undefined behavior, and thus the guest firmware will likely not boot
from the expected devices.

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@ -252,7 +252,10 @@ drive letters depend on the target architecture. The x86 PC uses: a, b
(floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p (Etherboot
from network adapter 1-4), hard disk boot is the default. To apply a
particular boot order only on the first startup, specify it via
@option{once}.
@option{once}. Note that the @option{order} or @option{once} parameter
should not be used together with the @option{bootindex} property of
devices, since the firmware implementations normally do not support both
at the same time.
Interactive boot menus/prompts can be enabled via @option{menu=on} as far
as firmware/BIOS supports them. The default is non-interactive boot.