From: Denis Mukhin <dmukhin@ford.com> 

Amends: 37339ba9ef46 ("automation: Remove XEN_CONFIG_EXPERT leftovers")
Signed-off-by: Denis Mukhin <dmukhin@ford.com>
---
Changes since v1:
- rephrased a note about EXPERT features
- Link to v1: https://lore.kernel.org/xen-devel/20260108141641.506534-2-dmukhin@ford.com/
---
 INSTALL | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/INSTALL b/INSTALL
index c2e756bf4b2b..919e1c04891b 100644
--- a/INSTALL
+++ b/INSTALL
@@ -33,11 +33,11 @@ small subset of the options.  Attempts to change other options will be
 silently overridden.  The only way to find which configuration options
 are available is to run `make menuconfig' or the like.
 
-You can counter-override this behaviour by setting XEN_CONFIG_EXPERT=y
-in your environment.  However, doing this is not supported and the
-resulting configurations do not receive security support.  If you set
-this variable there is nothing stopping you setting dangerously
-experimental combinations of features - not even any warnings.
+This behavior can be overridden by enabling "Configure EXPERT features"
+in Kconfig (CONFIG_EXPERT). However, resulting configurations do not
+receive security support. In addition, CONFIG_EXPERT permits the
+selection of experimental and potentially unsafe feature combinations
+without generating configuration warnings.
 
 Options recognized by configure
 ===============================
-- 
2.52.0

On 16.01.2026 04:08, dmukhin@xen.org wrote:
> --- a/INSTALL
> +++ b/INSTALL
> @@ -33,11 +33,11 @@ small subset of the options.  Attempts to change other options will be
>  silently overridden.  The only way to find which configuration options
>  are available is to run `make menuconfig' or the like.

I fear this earlier paragraph needs editing as well, which will then
make more clear that ...

> -You can counter-override this behaviour by setting XEN_CONFIG_EXPERT=y
> -in your environment.  However, doing this is not supported and the
> -resulting configurations do not receive security support.  If you set
> -this variable there is nothing stopping you setting dangerously
> -experimental combinations of features - not even any warnings.
> +This behavior can be overridden by enabling "Configure EXPERT features"
> +in Kconfig (CONFIG_EXPERT).

... this may not be quite adequate.

Jan

> However, resulting configurations do not
> +receive security support. In addition, CONFIG_EXPERT permits the
> +selection of experimental and potentially unsafe feature combinations
> +without generating configuration warnings.

On Fri, 16 Jan 2026, Jan Beulich wrote:
> On 16.01.2026 04:08, dmukhin@xen.org wrote:
> > --- a/INSTALL
> > +++ b/INSTALL
> > @@ -33,11 +33,11 @@ small subset of the options.  Attempts to change other options will be
> >  silently overridden.  The only way to find which configuration options
> >  are available is to run `make menuconfig' or the like.
> 
> I fear this earlier paragraph needs editing as well, which will then
> make more clear that ...
> 
> > -You can counter-override this behaviour by setting XEN_CONFIG_EXPERT=y
> > -in your environment.  However, doing this is not supported and the
> > -resulting configurations do not receive security support.  If you set
> > -this variable there is nothing stopping you setting dangerously
> > -experimental combinations of features - not even any warnings.
> > +This behavior can be overridden by enabling "Configure EXPERT features"
> > +in Kconfig (CONFIG_EXPERT).
> 
> ... this may not be quite adequate.
> 

I am not sure how you would like to change the earlier paragraph or this
paragraph. I gave it a try and removed both paragraphs, replacing it
with this:

"""
Only a subset of options is supported or security-supported by Xen
Project. You can explore all available options, including unsupported
ones and those recommended only for expert users, by using `make
menuconfig` and enabling `CONFIG_UNSUPPORTED` and/or `CONFIG_EXPERT`.
However, enabling these options is not supported, and configurations
resulting from them do not receive security support.
"""

What do you think?


> > However, resulting configurations do not
> > +receive security support. In addition, CONFIG_EXPERT permits the
> > +selection of experimental and potentially unsafe feature combinations
> > +without generating configuration warnings.

On 16.01.2026 21:47, Stefano Stabellini wrote:
> On Fri, 16 Jan 2026, Jan Beulich wrote:
>> On 16.01.2026 04:08, dmukhin@xen.org wrote:
>>> --- a/INSTALL
>>> +++ b/INSTALL
>>> @@ -33,11 +33,11 @@ small subset of the options.  Attempts to change other options will be
>>>  silently overridden.  The only way to find which configuration options
>>>  are available is to run `make menuconfig' or the like.
>>
>> I fear this earlier paragraph needs editing as well, which will then
>> make more clear that ...
>>
>>> -You can counter-override this behaviour by setting XEN_CONFIG_EXPERT=y
>>> -in your environment.  However, doing this is not supported and the
>>> -resulting configurations do not receive security support.  If you set
>>> -this variable there is nothing stopping you setting dangerously
>>> -experimental combinations of features - not even any warnings.
>>> +This behavior can be overridden by enabling "Configure EXPERT features"
>>> +in Kconfig (CONFIG_EXPERT).
>>
>> ... this may not be quite adequate.
>>
> 
> I am not sure how you would like to change the earlier paragraph or this
> paragraph. I gave it a try and removed both paragraphs, replacing it
> with this:
> 
> """
> Only a subset of options is supported or security-supported by Xen
> Project. You can explore all available options, including unsupported
> ones and those recommended only for expert users, by using `make
> menuconfig` and enabling `CONFIG_UNSUPPORTED` and/or `CONFIG_EXPERT`.
> However, enabling these options is not supported, and configurations
> resulting from them do not receive security support.
> """
> 
> What do you think?

This would be fine with me.

Jan

On Mon, Jan 19, 2026 at 08:29:58AM +0100, Jan Beulich wrote:
> On 16.01.2026 21:47, Stefano Stabellini wrote:
> > On Fri, 16 Jan 2026, Jan Beulich wrote:
> >> On 16.01.2026 04:08, dmukhin@xen.org wrote:
> >>> --- a/INSTALL
> >>> +++ b/INSTALL
> >>> @@ -33,11 +33,11 @@ small subset of the options.  Attempts to change other options will be
> >>>  silently overridden.  The only way to find which configuration options
> >>>  are available is to run `make menuconfig' or the like.
> >>
> >> I fear this earlier paragraph needs editing as well, which will then
> >> make more clear that ...
> >>
> >>> -You can counter-override this behaviour by setting XEN_CONFIG_EXPERT=y
> >>> -in your environment.  However, doing this is not supported and the
> >>> -resulting configurations do not receive security support.  If you set
> >>> -this variable there is nothing stopping you setting dangerously
> >>> -experimental combinations of features - not even any warnings.
> >>> +This behavior can be overridden by enabling "Configure EXPERT features"
> >>> +in Kconfig (CONFIG_EXPERT).
> >>
> >> ... this may not be quite adequate.
> >>
> > 
> > I am not sure how you would like to change the earlier paragraph or this
> > paragraph. I gave it a try and removed both paragraphs, replacing it
> > with this:
> > 
> > """
> > Only a subset of options is supported or security-supported by Xen
> > Project. You can explore all available options, including unsupported
> > ones and those recommended only for expert users, by using `make
> > menuconfig` and enabling `CONFIG_UNSUPPORTED` and/or `CONFIG_EXPERT`.
> > However, enabling these options is not supported, and configurations
> > resulting from them do not receive security support.
> > """
> > 
> > What do you think?
> 
> This would be fine with me.

Thanks Stefano and Jan.
I will send an update shortly.

--
Denis