[PATCH v2] ref-manual/variables.rst: document the QB_DEFAULT_BIOS variable

[PATCH v2] ref-manual/variables.rst: document the QB_DEFAULT_BIOS variable

[Antonin Godard]

The QB_DEFAULT_BIOS allows setting the -bios parameter of QEMU, which
can be used to emulate U-Boot, for example.

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
---
Changes in v2:
- Address comments from Quentin (thanks!)
- Link to v1: https://patch.msgid.link/20260804-qb-default-bios-v1-1-bc851931973d@bootlin.com
---
 documentation/ref-manual/variables.rst | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index e75f42afe..f4ed9a883 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -8084,6 +8084,25 @@ system and gives an overview of their function and contents.
       replaces the ``@CLIENT@`` and ``@GATEWAY@`` place holders by the IP and
       the gateway address of the QEMU guest.
 
+   :term:`QB_DEFAULT_BIOS`
+      The :term:`QB_DEFAULT_BIOS` variable can be used to provide a default
+      value for the path the of a file located in :term:`DEPLOY_DIR_IMAGE` and
+      used by ``runqemu`` to specify the `-bios <https://www.qemu.org/docs/master/system/invocation.html#hxtool-8>`__
+      option of QEMU. For example, this parameter can be set as follows to
+      emulate U-Boot for the :oecore_path:`qemuarm64 <meta/conf/machine/qemuarm64.conf>`
+      machine::
+
+         QB_DEFAULT_BIOS = "u-boot.bin"
+
+      The above example makes the assumption the U-Boot recipe was built
+      and that the ``u-boot.bin`` is deployed in the :term:`DEPLOY_DIR_IMAGE`
+      directory.
+
+      .. note::
+
+         When using ``runqemu``, the ``BIOS`` environment variable takes
+         precedence over this variable.
+
    :term:`QB_DEFAULT_FSTYPE`
 
       The :term:`QB_DEFAULT_FSTYPE` variable controls the default filesystem

---
base-commit: 41dae3c3da3ada1745fc60228ff6269c64ee2361
change-id: 20260804-qb-default-bios-7c12e88f0db2

Re: [docs] [PATCH v2] ref-manual/variables.rst: document the QB_DEFAULT_BIOS variable

[Quentin Schulz]

Hi Antonin,

On 8/11/26 3:17 PM, Antonin Godard via lists.yoctoproject.org wrote:
> The QB_DEFAULT_BIOS allows setting the -bios parameter of QEMU, which
> can be used to emulate U-Boot, for example.
> 
> Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
> ---
> Changes in v2:
> - Address comments from Quentin (thanks!)
> - Link to v1: https://patch.msgid.link/20260804-qb-default-bios-v1-1-bc851931973d@bootlin.com
> ---
>   documentation/ref-manual/variables.rst | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
> 
> diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
> index e75f42afe..f4ed9a883 100644
> --- a/documentation/ref-manual/variables.rst
> +++ b/documentation/ref-manual/variables.rst
> @@ -8084,6 +8084,25 @@ system and gives an overview of their function and contents.
>         replaces the ``@CLIENT@`` and ``@GATEWAY@`` place holders by the IP and
>         the gateway address of the QEMU guest.
>   
> +   :term:`QB_DEFAULT_BIOS`
> +      The :term:`QB_DEFAULT_BIOS` variable can be used to provide a default

"can be used to provide a default value" can be read as "it's not 
mandatory" while it is when using runqemu (well, that or the BIOS 
environment variable).

> +      value for the path the of a file located in :term:`DEPLOY_DIR_IMAGE` and

"to provide the path to a file located in"?

if you don't want that, there is some syntax issue here (likely a 
spurious "the").

> +      used by ``runqemu`` to specify the `-bios <https://www.qemu.org/docs/master/system/invocation.html#hxtool-8>`__
> +      option of QEMU. For example, this parameter can be set as follows to

s/parameter/variable/

Cheers,
Quentin

Re: [docs] [PATCH v2] ref-manual/variables.rst: document the QB_DEFAULT_BIOS variable

[Antonin Godard]

Hi,

On Tue Aug 11, 2026 at 3:31 PM CEST, Quentin Schulz via lists.yoctoproject.org wrote:
> Hi Antonin,
>
> On 8/11/26 3:17 PM, Antonin Godard via lists.yoctoproject.org wrote:
>> The QB_DEFAULT_BIOS allows setting the -bios parameter of QEMU, which
>> can be used to emulate U-Boot, for example.
>> 
>> Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
>> ---
>> Changes in v2:
>> - Address comments from Quentin (thanks!)
>> - Link to v1: https://patch.msgid.link/20260804-qb-default-bios-v1-1-bc851931973d@bootlin.com
>> ---
>>   documentation/ref-manual/variables.rst | 19 +++++++++++++++++++
>>   1 file changed, 19 insertions(+)
>> 
>> diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
>> index e75f42afe..f4ed9a883 100644
>> --- a/documentation/ref-manual/variables.rst
>> +++ b/documentation/ref-manual/variables.rst
>> @@ -8084,6 +8084,25 @@ system and gives an overview of their function and contents.
>>         replaces the ``@CLIENT@`` and ``@GATEWAY@`` place holders by the IP and
>>         the gateway address of the QEMU guest.
>>   
>> +   :term:`QB_DEFAULT_BIOS`
>> +      The :term:`QB_DEFAULT_BIOS` variable can be used to provide a default
>
> "can be used to provide a default value" can be read as "it's not 
> mandatory" while it is when using runqemu

It's not? Using runqemu with qemuarm64 and _without_ a BIOS value (or
QB_DEFAULT_BIOS) is possible. In fact it's the default behavior.

Antonin

Re: [docs] [PATCH v2] ref-manual/variables.rst: document the QB_DEFAULT_BIOS variable

[Quentin Schulz]

On 8/11/26 4:16 PM, Antonin Godard wrote:
> Hi,
> 
> On Tue Aug 11, 2026 at 3:31 PM CEST, Quentin Schulz via lists.yoctoproject.org wrote:
>> Hi Antonin,
>>
>> On 8/11/26 3:17 PM, Antonin Godard via lists.yoctoproject.org wrote:
>>> The QB_DEFAULT_BIOS allows setting the -bios parameter of QEMU, which
>>> can be used to emulate U-Boot, for example.
>>>
>>> Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
>>> ---
>>> Changes in v2:
>>> - Address comments from Quentin (thanks!)
>>> - Link to v1: https://patch.msgid.link/20260804-qb-default-bios-v1-1-bc851931973d@bootlin.com
>>> ---
>>>    documentation/ref-manual/variables.rst | 19 +++++++++++++++++++
>>>    1 file changed, 19 insertions(+)
>>>
>>> diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
>>> index e75f42afe..f4ed9a883 100644
>>> --- a/documentation/ref-manual/variables.rst
>>> +++ b/documentation/ref-manual/variables.rst
>>> @@ -8084,6 +8084,25 @@ system and gives an overview of their function and contents.
>>>          replaces the ``@CLIENT@`` and ``@GATEWAY@`` place holders by the IP and
>>>          the gateway address of the QEMU guest.
>>>    
>>> +   :term:`QB_DEFAULT_BIOS`
>>> +      The :term:`QB_DEFAULT_BIOS` variable can be used to provide a default
>>
>> "can be used to provide a default value" can be read as "it's not
>> mandatory" while it is when using runqemu
> 
> It's not? Using runqemu with qemuarm64 and _without_ a BIOS value (or
> QB_DEFAULT_BIOS) is possible. In fact it's the default behavior.
> 

I misread runqemu, sorry for the noise. I missed the early return.

Cheers,
Quentin