[PATCH] bootstd: Allow PXE boot to be disabled

[Simon Glass]

Hi Tony,

On Sat, 11 Oct 2025 at 20:41, Tony Dinh <mibodhi at gmail.com> wrote:
>
> On Sat, Oct 11, 2025 at 7:37 AM Tom Rini <trini at konsulko.com> wrote:
> >
> > On Sat, Oct 11, 2025 at 01:03:39PM +0100, Peter Robinson wrote:
> > > On Fri, 10 Oct 2025 at 15:28, Tom Rini <trini at konsulko.com> wrote:
> > > >
> > > > On Thu, Oct 09, 2025 at 10:29:17PM -0700, Tony Dinh wrote:
> > > >
> > > > > Make it possible to disable CMD_PXE.
> > > > > Remove unnecessary PXE_UTILS selection in BOOTMETH_EXTLINUX config.
> > > > > In extlinux_boot(), invoke pxe utils only when
> > > > > CONFIG_BOOTMETH_EXTLINUX_PXE is enabled.
> > > > >
> > > > > This patch results in about 9K reduction in image size when
> > > > > PXE boot is disabled.
> > > > >
> > > > > Signed-off-by: Tony Dinh <mibodhi at gmail.com>
> > > > > ---
> > > > >
> > > > >  boot/Kconfig             |  3 +--
> > > > >  boot/bootmeth_extlinux.c | 18 ++++++++++--------
> > > > >  2 files changed, 11 insertions(+), 10 deletions(-)
> > > >
> > > > Is some part of the symbol logic here wrong? A challenge is that "PXE"
> > > > is also where the logic to parse extlinux.conf style files came from,
> > > > and I thought we had split those two out. And then there's this:
> > > >
> > > > >
> > > > > diff --git a/boot/Kconfig b/boot/Kconfig
> > > > > index 2993cd7f9ba..403ce4c3d46 100644
> > > > > --- a/boot/Kconfig
> > > > > +++ b/boot/Kconfig
> > > > > @@ -421,10 +421,10 @@ config BOOT_DEFAULTS_CMDS
> > > > >       select CMD_PART if PARTITIONS
> > > > >       select CMD_DHCP if CMD_NET
> > > > >       select CMD_PING if CMD_NET
> > > > > -     select CMD_PXE if CMD_NET
> > > > >       select CMD_BOOTI if ARM64
> > > > >       select CMD_BOOTZ if ARM && !ARM64
> > > > >       imply CMD_MII if NET
> > > > > +     imply CMD_PXE if CMD_NET

If you only want scripts, then perhaps you can enable just what you
need, e.g. BOOTMETH_SCRIPT? You may need to disable BOOT_DEFAULTS and
choose your own options.

> > > >
> > > > This is one of the things where defaults isn't supposed to be so easy to
> > > > get out of. How many platforms are you wanting to then disable CMD_PXE
> > > > on to save space?
> > >
> > > PXE is generally being removed in a lot of cases as it's not
> > > considered secure and now we have HTTP Boot there are other means of
> > > doing network booting so I think we'll see more and more situations
> > > where we want to disable PXE.
> > >
> > > This is actually something I've been meaning to look at so it's
> > > something I would love to see :)
>
> Glad to hear :)
>
> >
> > And in the world where we also can't just remove ATAGS support because
> > distros (Debian at least) still boots some modern platforms via ATAGS +
> > appended device tree, the high level options for "boot this anywhere"
> > need to perhaps be different from "very modern requirements only
> > distro". I'm not objecting to be clear.
>
> As Tom suggested previously, perhaps looking from a different angle.
> We can disable BOOTSTD_FULL and then try adding only options that are
> needed for a board. Unfortunately this approach did not work when I
> tried it in the past. It seems for bootstd to work well, we need to
> take the whole thing by enabling BOOTSTD_FULL.

If you end up trying it again, please give a few details here as we
might be able to improve this. When bootstd was first introduced we
had very tight code-size constraints, so quite a few features are only
provided if BOOTSTD_FULL is enabled. Tom has suggested enabling more
features in the base implementation but we haven't really figured out
which.

Regards,
Simon