How to add kernel parameters to installer boot?

[Arne Pisch]

Well as already mentioned just modify grub.cfg.
Another alternative would be chainloading the iso. This way it wouldn't 
even be modified while being able to customize menus.

It depends on the purpose and the process which way to go.
Personally I always found especially the mini.iso useful as is excluding 
environments with uboot where prebuilt images are the preferred way . 
Also I prefer the daily builds to not run into dependency issues where no 
matching kernel can be found in the repo.

Re: How to add kernel parameters to installer boot?

[Lennart Sorensen]

On Wed, Jul 15, 2026 at 11:14:24AM +0200, Marc Haber wrote:
> when I am building my own image (here: a mini.iso) anyway, where would I add
> kernel parameters I want the installer to boot with?
> 
> Did I see correctly that on amd64, classical BIOS/CSM machines still boot
> using isolinux while EFI boots with grub?

I believe you need to look at /debian-installer/installer/build/config/x86.cfg

It calls the scripts for generating syslinux, isolinux, grub2 efi,
etc for making the iso.  So for EFI boot, it looks like you could add
something after
grub-gencfg \
KERNEL /linux \
INITRD /initrd.gz \
HEADER boot/x86/grub/grub-efi.cfg \
IS_PURE_GTK "$(IS_PURE_GTK)" \
IS_X86 1 \
-- \
$(VIDEO_MODE) \

For isolinux or syslinux boot it would have to be done differently since
each one has it's own way of generating the boot menu and what options
it has.  There does not appear to be any variable to add extra values
to the kernel in general.

-- 
Len Sorensen

Re: How to add kernel parameters to installer boot?

[Cyril Brulebois]

Hi,

Pascal Hambourg  (2026-07-15):
> On 15/07/2026 at 11:14, Marc Haber wrote:
> > 
> > when I am building my own image (here: a mini.iso) anyway, where
> > would I add kernel parameters I want the installer to boot with?
> 
> In the boot loader menu entry config file(s).

I looked around when the question came in, and that's basically what I
would have answered as well.

Back from a non-technical detour, I seem to remember having (ab)used the
VIDEO_MODE variable to inject some extra options in the past. It's all
kinds of wrong, but looking at the config files, that should do the
trick for all/most menu entries (incl. rescue, expert, etc.), but I
haven't toyed with it recently.

This might may or may not be better than adjusting one or two entries
specifically, depending on the considered use case.


Cheers,
-- 
Cyril Brulebois (k...@debian.org)
D-I release manager -- Release team member -- Freelance Consultant


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How to be more respectful of others (was: How to add kernel parameters to installer boot?)

[Cyril Brulebois]

Hi,

Marc Haber  (2026-07-15):
> On Wed, Jul 15, 2026 at 04:32:07PM +0200, an anonymous gmail user
> masquerading as "john doe" wrote:
> > On 7/15/26 4:02 PM, Marc Haber wrote:
> > > Duh, that was not a very helpful answer. I am still trying to find
> > > my way around the huge amount of packages and sources, and I
> > > wouldn't have asked that question if I had found the files to
> > > change.

And yet, Pascal's answer is perfectly valid and to the point, there is
no “the one central place where kernel options are hidden and we don't
want to tell Marc about” place (that I'm aware of). It depends on the
menu entry you want to boot from, which also depends on BIOS vs. UEFI,
which is a topic that Pascal also provided a correct answer for.

In contrast, your answer is rather rude, and I would understand it if
it would lead people to steering clear of those threads, instead of
getting them more involved.

> > You are the one wanting help, you are better off rephrasing your
> > question if you want a meaningful answer.
> 
> Who are you to talk down to a (fellow?) Debian Developer in this way?
> What are your contributions to Debian in the last 25 years?

Seeing people ask several questions, get answers within a very short
timeframe, and appear unhappy about those answers to the tone of “duh”…
is something I would prefer *not* witnessing on this list (or any). And
that, regardless of the DD-ness and amount of contributions over any
timeframe, on either side.


Cheers,
-- 
Cyril Brulebois (k...@debian.org)
D-I release manager -- Release team member -- Freelance Consultant


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Re: How to add kernel parameters to installer boot?

[Marc Haber]

Hi,

On Wed, Jul 15, 2026 at 04:32:07PM +0200, an anonymous gmail user 
masquerading as "john doe" wrote:

On 7/15/26 4:02 PM, Marc Haber wrote:
Duh, that was not a very helpful answer. I am still trying to find 
my way around the huge amount of packages and sources, and I 
wouldn't have asked that question if I had found the files to 
change.


You are the one wanting help, you are better off rephrasing your 
question if you want a meaningful answer.


Who are you to talk down to a (fellow?) Debian Developer in this way? 
What are your contributions to Debian in the last 25 years?


Greetings
Marc

--
-
Marc Haber | "I don't trust Computers. They | Mailadresse im Header
Leimen, Germany|  lose things."Winona Ryder | Fon: *49 6224 1600402
Nordisch by Nature |  How to make an American Quilt | Fax: *49 6224 1600421

Re: How to add kernel parameters to installer boot?

[john doe]

On 7/15/26 4:02 PM, Marc Haber wrote:

On Wed, Jul 15, 2026 at 12:54:23PM +0200, Pascal Hambourg wrote:

On 15/07/2026 at 11:14, Marc Haber wrote:
when I am building my own image (here: a mini.iso) anyway, where 
would I add kernel parameters I want the installer to boot with?


In the boot loader menu entry config file(s).


Duh, that was not a very helpful answer. I am still trying to find my 
way around the huge amount of packages and sources, and I wouldn't have 
asked that question if I had found the files to change.


You are the one wanting help, you are better off rephrasing your 
question if you want a meaningful answer.



Using PXEbooting, I have to modify grub.cfg or one of the *.cfg file in 
boot-screens subdirectory.


--
John Doe

Re: How to add kernel parameters to installer boot?

[Marc Haber]

On Wed, Jul 15, 2026 at 12:54:23PM +0200, Pascal Hambourg wrote:

On 15/07/2026 at 11:14, Marc Haber wrote:
when I am building my own image (here: a mini.iso) anyway, where 
would I add kernel parameters I want the installer to boot with?


In the boot loader menu entry config file(s).


Duh, that was not a very helpful answer. I am still trying to find my 
way around the huge amount of packages and sources, and I wouldn't have 
asked that question if I had found the files to change.


Did I see correctly that on amd64, classical BIOS/CSM machines still 
boot using isolinux while EFI boots with grub?

Yes.


Then I would like to mention that grml, for example, changed to a 
grub-only scheme on amd64 with quite some success which has eased 
development considerably since the whole isolinux stuff could go away.  
Maybe things are a bit more complicated for d-i, I understand that d-i 
supports way more arches than grml does, and that the d-i team seems to 
be grossly understaffed, but maybe changing to a grub-only setup would 
be beneficial for the installer as well.


Greetings
Marc

--
-
Marc Haber | "I don't trust Computers. They | Mailadresse im Header
Leimen, Germany|  lose things."Winona Ryder | Fon: *49 6224 1600402
Nordisch by Nature |  How to make an American Quilt | Fax: *49 6224 1600421

Re: How to add kernel parameters to installer boot?

[Pascal Hambourg]

On 15/07/2026 at 11:14, Marc Haber wrote:


when I am building my own image (here: a mini.iso) anyway, where would I 
add kernel parameters I want the installer to boot with?


In the boot loader menu entry config file(s).

Did I see correctly that on amd64, classical BIOS/CSM machines still 
boot using isolinux while EFI boots with grub?

Yes.

How to add kernel parameters to installer boot?

[Marc Haber]

Hi,

when I am building my own image (here: a mini.iso) anyway, where would I 
add kernel parameters I want the installer to boot with?


Did I see correctly that on amd64, classical BIOS/CSM machines still 
boot using isolinux while EFI boots with grub?


Greetings
Marc

--
-
Marc Haber | "I don't trust Computers. They | Mailadresse im Header
Leimen, Germany|  lose things."Winona Ryder | Fon: *49 6224 1600402
Nordisch by Nature |  How to make an American Quilt | Fax: *49 6224 1600421