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

Wed Oct 23 20:41:30 CEST 2024

On Tue, Oct 22, 2024 at 07:00:44PM +0200, Simon Glass wrote:
> Hi Tom,
> 
> On Tue, 22 Oct 2024 at 17:01, Tom Rini <trini at konsulko.com> wrote:
> >
> > On Tue, Oct 22, 2024 at 02:16:52PM +0200, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Sat, 19 Oct 2024 at 18:30, Tom Rini <trini at konsulko.com> wrote:
> > > >
> > > > On Sat, Oct 19, 2024 at 05:49:40AM -0600, Simon Glass wrote:
> > > > > 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.
> > > >
> > > > And the distro scripts are functionally replaced by "bootefi bootmgr",
> > > > outside of bootstd.
> > >
> > > But that doesn't support anything other than EFI apps, so isn't useful
> > > for when EFI is not wanted.
> >
> > Yes, the distro scripts wanted to move more firmly / quickly in this
> > direction. For all of the reasons they've elaborated before.
> 
> OK, well good luck to them, I suppose.
> 
> >
> > > > > > > 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!
> > > >
> > > > I wasn't clear enough, sorry. I didn't mean just in this series where
> > > > you referred to storing the needed property as a hack but rather
> > > > "bolt-on" in what I quoted and "tidy up this" and "tidy up that". I'm
> > > > just saying what impression your words leave with me, and quite possibly
> > > > others.
> > >
> > > OK I will try to be more gentle with my language.
> >
> > Thanks.
> >
> > > > > > > > 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.
> > > >
> > > > OK. But that's not generic enough.
> > >
> > > How about we see how things work out here rather than giving up at the
> > > start? It is pretty clear in my head, so far.
> >
> > I'd really rather not since it looks like it's starting in the wrong
> > direction. I really do not understand why when we load the file / do the
> > network request / read the flash area / etc is the wrong place to start
> > recording the information about what we load.
> 
> It isn't that it is the wrong place, it's just that we know more when
> a bootmeth is in place. Are you thinking about the distro scripts or
> people's custom scripts, or something else?
[snip]
> > Yes, perhaps some series that shows what works / doesn't work and how it
> > works would be helpful. I'd really like to see where you're starting
> > your abstractions from.
> 
> OK I'll send a version with an add-on patch for the 'load' command,
> with the concept of an ad-hoc bootflow.

I want to combine these two (and I hope not drop any important context),
to reply. A challenge is that for EFI, we need to know where we loaded
something from. You hope that EFI_LOADER will make use of bootmeths at
some future point, but that's not on your TODO list? What I'm saying is
that in for example fs_read(), we have the common point between
bootmeth, EFI_LOADER and "load" and already need to be doing sanity
checks and can record what information we have now. Can bootmeth add to
it? Sure. But I still don't see why this is the wrong place to start.
And there are analogous points for network, flash, etc.

-- 
Tom
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