[PATCH 1/2 v2] smbios: Simplify reporting of unknown values

[Peter Robinson]

Hi Simon,

On Mon, Dec 18, 2023 at 3:02 PM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Ilias,
>
> On Wed, 6 Dec 2023 at 04:36, Ilias Apalodimas
> <ilias.apalodimas at linaro.org> wrote:
> >
> > [...]
> >
> > >
> > >>
> > >> >                 str = "Unknown";
> > >> >
> > >> >         for (;;) {
> > >> > @@ -151,8 +151,7 @@ static int smbios_add_prop_si(struct smbios_ctx *ctx, const char *prop,
> > >> >                 const char *str;
> > >> >
> > >> >                 str = ofnode_read_string(ctx->node, prop);
> > >> > -               if (str)
> > >> > -                       return smbios_add_string(ctx, str);
> > >> > +               return smbios_add_string(ctx, str);
> > >> >         }
> > >> >
> > >> >         return 0;
> > >> > @@ -231,7 +230,7 @@ static int smbios_write_type0(ulong *current, int handle,
> > >> >         t->vendor = smbios_add_string(ctx, "U-Boot");
> > >> >
> > >> >         t->bios_ver = smbios_add_prop(ctx, "version");
> > >> > -       if (!t->bios_ver)
> > >> > +       if (!strcmp(ctx->last_str, "Unknown"))
> > >>
> > >> That is really ugly...checking the ctx value looking for a side effect.
> > >>
> > >> Can you not have smbios_add_prop() continue to return NULL in this case?
> > >
> > >
> > > Hmm I don't know, but I wonder why I am not just checking t->bios_ver for Unknown.
> > > I'll have a look and change it
> >
> > Ok, this can't be changed as easily.  smbios_add_prop() will not
> > return NULL in any case. It returns an integer. With the cleanup, it
> > will always writes 'Uknown' and not return 0 anymore.
> > I can add that default value you suggested but the ctx->last_str is
> > still used on the next line anyway.
>
> Would you mind if I tried to create a version of the patch which does
> the same thing but with less code, and perhaps a test? It might be
> easier to discuss it then. I can't claim to understand all the
> different code paths at this point.
>
> My main concern is that with so many code paths it will be hard even
> to refactor the code in the future, since it will become
> 'load-bearing' and anyone might turn up and say it breaks their board
> because different information is provided.

I don't buy this argument at all, sorry.

> Overall, so long as the information isn't used for anything important
> in userspace, and we find a way to report SMBIOS to Linux without EFI,

No, you can't tie random requirements to improving the SMBIOS support.
We *already* report SMBIOS to Linux, reporting SMBIOS to Linux without
EFI is changing things that will need different or extra standards,
that could take years.

You are arbitrarily adding extra requirements just to suite yourself,
please STOP trying to hold things like this hostage.

> it is OK to enable this feature (with a new Kconfig so it can be
> disabled). But there is already authoritative info in the DT, so this

There is two types of information in DT, the smbios "entries" in DT
are not standardised in the dtschema and in most cases they're
unnecessarily replicating data ALREADY in DT which is being produced
automatically with these patches, making it zero effort for vendors to
produce.

> transformation into SMBIOS really should just be used for user
> display, etc., not for anything which affects operation of the device.

Well SMBIOS tables are used for a number of different things already
in the kernel.

> Do you agree? If you do, how to ensure that? Perhaps a special string
> in the table like 'GENERATED'?

Nope, I do not agree, at all.

Regards,
Peter