[Qemu-devel] [PATCH] docs: Add a note about mixing bootindex with "-boot order"

[Qemu-devel] [PATCH] docs: Add a note about mixing bootindex with "-boot order"

[Thomas Huth]

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>
---
 docs/bootindex.txt | 9 +++++++++
 qemu-options.hx    | 5 ++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/docs/bootindex.txt b/docs/bootindex.txt
index f84fac7..9e0ac07 100644
--- a/docs/bootindex.txt
+++ b/docs/bootindex.txt
@@ -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.
diff --git a/qemu-options.hx b/qemu-options.hx
index bf458f8..aa11420 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -234,7 +234,10 @@ 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.
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH] docs: Add a note about mixing bootindex with "-boot order"

[Eric Blake]

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On 02/28/2017 11:40 AM, Thomas Huth wrote:
> 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>
> ---
>  docs/bootindex.txt | 9 +++++++++
>  qemu-options.hx    | 5 ++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH] docs: Add a note about mixing bootindex with "-boot order"

[Laszlo Ersek]

On 02/28/17 18:40, Thomas Huth wrote:
> 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>
> ---
>  docs/bootindex.txt | 9 +++++++++

Wow, a document from 2011!

commit 466b58648a7b2ba7edb280b585e0b0c26e3be31e
Author: Gleb Natapov <gleb@redhat.com>
Date:   Sun Jan 30 12:29:19 2011 +0200

    Add boot index documentation.

So cool. I didn't know this existed.

>  qemu-options.hx    | 5 ++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/bootindex.txt b/docs/bootindex.txt
> index f84fac7..9e0ac07 100644
> --- a/docs/bootindex.txt
> +++ b/docs/bootindex.txt
> @@ -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.
> diff --git a/qemu-options.hx b/qemu-options.hx
> index bf458f8..aa11420 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -234,7 +234,10 @@ 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.
> 

Awesome. Thank you for this.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>