[PATCH 23/34] bootstd: Maintain a list of images

[Simon Glass]

Hi Tom,

On Fri, 18 Oct 2024 at 15:30, Tom Rini <trini at konsulko.com> wrote:
>
> On Fri, Oct 18, 2024 at 12:48:31PM -0600, Simon Glass wrote:
> > Hi Tom,
> >
> > On Fri, 18 Oct 2024 at 12:04, Tom Rini <trini at konsulko.com> wrote:
> > >
> > > On Fri, Oct 18, 2024 at 11:20:52AM -0600, Simon Glass wrote:
> > > > Hi Tom,
> > > >
> > > > On Fri, 18 Oct 2024 at 10:33, Tom Rini <trini at konsulko.com> wrote:
> > > > >
> > > > > On Fri, Oct 18, 2024 at 09:01:03AM -0600, Simon Glass wrote:
> > > > > > Hi Heinrich,
> > > > > >
> > > > > > On Thu, 17 Oct 2024 at 22:07, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > Am 18. Oktober 2024 01:24:02 MESZ schrieb Simon Glass <sjg at chromium.org>:
> > > > > > > >We want to keep track of images which are loaded, or those which could
> > > > > > > >perhaps be loaded. This will make it easier to manage memory allocation,
> > > > > > > >as well as permit removal of the EFI set_efi_bootdev() hack.
> > > > > >
> > > > > > I'll change this 'hack' to 'feature'.
> > > > > >
> > > > > > >
> > > > > > > Please, keep in mind that files can be loaded manually, e.g. via the dhcp, the wget, and the loady commands. These are outside bootflows.
> > > > > >
> > > > > > Yes, this series is only going to help if bootstd is used. For ad-hoc
> > > > > > use, EFI will need to rely on the above feature, at least until
> > > > > > someone can think of another solution.
> > > > >
> > > > > Perhaps I need to try and be clearer here than I might have been in the
> > > > > past. The consensus among off the shelf free software operating systems
> > > > > is "just give me an EFI interface". This simplifies things on their end
> > > > > if regardless of architecture it's the same interface. This means that
> > > > > in U-Boot we need to treat EFI as one of the primary interfaces. Not a
> > > > > novelty. Not a "some people might use". It is a frequent and commonly
> > > > > used feature.
> > > >
> > > > Yes, EFI is everywhere and growing. All the more reason to tidy up
> > > > this piece. I would like to see bootmgr use this new API, for example.
> > > >
> > > > But how does this comment affect this patch?
> > >
> > > Because at the very high level, I wonder if I made a mistake a few years
> > > back. As I understand it, the nominal case is "bootefi bootmgr". I was
> > > saying at the time that perhaps bootstd can just fire that off, and move
> > > on. Now it seems like we're going along the path of re-inventing that,
> > > and not integrating well with it either.
> >
> > In what way are we re-inventing that? bootstd supports lots of
> > different ways of booting, not just EFI.
>
> At the high level, bootflow scan is re-implementing "bootefi bootmgr".
> but handling non-EFI payloads.

bootstd is about replacing the distro scripts, not bootmgr.

>
> > Also I hope that one day EFI
> > will be implemented more as part of U-Boot than as a bolt-on, so will
> > make use of bootflows, etc.
>
> And stuff like that is why I said what I said in here first. To me it
> sounds like you keep implying it's a hack that's not well integrated.
> When it's honestly at this point gotten more traction than FIT images
> have I think (as much as I wish FIT images had "won", it's like VHS vs
> Betamax, to bring in another technology metaphor).

The 'hack' I was referring to is efi_set_bootdev(), not EFI_LOADER as a whole!

>
> > > So, to try and bring things back together. If U-Boot decides to load
> > > $FOO from device $BAR, at that common point is where we need to:
> > > - Is there an lmb for the location this is supposed to go to (for the if
> > >   we know it, entire size)?
> > > - Note down everything else we know, now.
> >
> > Yes.
> >
> > >
> > > This means that we can note down enough stuff so that EFI can construct
> > > the path it needs. And if we're being told a filesystem, that filename
> > > is good enough for the IH_TYPE thing you're wanting, or at least a good
> > > chunk of it I hope.
> >
> > You want me to ignore the type that I know (kernel, ramdisk, logo,
> > etc.) and infer the type from a filename? Why?
>
> No, I want you to save and display the filename. That's probably much
> more useful when debugging than "kernel". If you actually know some
> other type information (ie extlinux.conf says ...) then yes, it too can
> be stored as that's useful too.

The filename is already saved in bootflow->filename, and now it is in
struct bootflow_img.

>
> > For EFI there is only an EFI application. It will always just be a PE
> > file. We don't really know what it is, as someone pointed out earlier.
> > Maybe one day we will check to see if it is a UKI and pull things out
> > of it. But then, it would be component parts (kernel, ramdisk, etc.)
> > so I would want to add them as images.
>
> I don't see why yet, honestly.

For the cmdline, 'bootflow cmdline' allows editing it, for example.
For a logo we can display it in the menu. The filename doesn't tell us
what it is.

>
> > > It also means that since it's at the most common point, it doesn't
> > > matter if we were in an EFI application, a boot script, a bootmeth or
> > > someone at the cmdline doing "load mmc 0:1 /boot/Image $kernel_addr_r".
> >
> > For that case (at the cmdline), bootstd is not currently running. Are
> > you suggesting that bootstd could pick up these things and record
> > them? If so, then yes, definitely, I want to do that. This series is
> > the starting point for that. If you are suggesting something else,
> > then I think I have lost you at this point.
>
> Yes, I think I lost you somewhere, but I'm not sure how. What I am
> saying is that since everything at some point calls down to say
> fs_read() to read a file, that is the common point to note what
> we're doing. Not the load command, not the bootmeth, not the EFI_LOADER
> call.

Perhaps what you are missing is that bootstd is a proper boot
implementation for U-Boot, where U-Boot knows what is going on.
Ignoring that information and just hooking into fs_read() is like
throwing away the plan and trying to recreate it from photographs.

That said, yes I can hook into fs_read() and store that info, as it is
better than nothing, if bootstd is not being used, or there is a
script.

Regards,
Simon