[PATCH 2/2] smbios: Fallback to the default DT if sysinfo nodes are missing

[Ilias Apalodimas]

Hi Simon, 

On Thu, Sep 29, 2022 at 03:59:51AM -0600, Simon Glass wrote:
> Hi,
> 
> On Tue, 20 Sept 2022 at 05:10, Peter Robinson <pbrobinson at gmail.com> wrote:
> >
> > On Tue, Sep 6, 2022 at 2:44 PM Ilias Apalodimas
> > <ilias.apalodimas at linaro.org> wrote:
> > >
> > > In order to fill in the SMBIOS tables U-Boot currently relies on a
> > > "u-boot,sysinfo-smbios" compatible node.  This is fine for the boards
> > > that already include such nodes.  However with some recent EFI changes,
> > > the majority of boards can boot up distros, which usually rely on
> > > things like dmidecode etc for their reporting.  For boards that
> > > lack this special node the SMBIOS output looks like:
> > >
> > > System Information
> > >         Manufacturer: Unknown
> > >         Product Name: Unknown
> > >         Version: Unknown
> > >         Serial Number: Unknown
> > >         UUID: Not Settable
> > >         Wake-up Type: Reserved
> > >         SKU Number: Unknown
> > >         Family: Unknown
> > >
> > > This looks problematic since most of the info are "Unknown".  The DT spec
> > > specifies standard properties containing relevant information like
> > > 'model' and 'compatible' for which the suggested format is
> > > <manufacturer,model>.  So let's add a last resort to our current
> > > smbios parsing.  If none of the sysinfo properties are found,  we can
> > > scan the root node for 'model' and 'compatible'.
> >
> > I don't think the information below all needs to go in the commit,
> > maybe in the cover letter?
> >
> > > pre-patch dmidecode:
> > > <snip>
> > > Handle 0x0001, DMI type 1, 27 bytes
> > > System Information
> > >         Manufacturer: Unknown
> > >         Product Name: Unknown
> > >         Version: Unknown
> > >         Serial Number: Unknown
> > >         UUID: Not Settable
> > >         Wake-up Type: Reserved
> > >         SKU Number: Unknown
> > >         Family: Unknown
> > >
> > > Handle 0x0002, DMI type 2, 14 bytes
> > > Base Board Information
> > >         Manufacturer: Unknown
> > >         Product Name: Unknown
> > >         Version: Unknown
> > >         Serial Number: Not Specified
> > >         Asset Tag: Unknown
> > >         Features:
> > >                 Board is a hosting board
> > >         Location In Chassis: Not Specified
> > >         Chassis Handle: 0x0000
> > >         Type: Motherboard
> > >
> > > Handle 0x0003, DMI type 3, 21 bytes
> > > Chassis Information
> > >         Manufacturer: Unknown
> > >         Type: Desktop
> > >         Lock: Not Present
> > >         Version: Not Specified
> > >         Serial Number: Not Specified
> > >         Asset Tag: Not Specified
> > >         Boot-up State: Safe
> > >         Power Supply State: Safe
> > >         Thermal State: Safe
> > >         Security Status: None
> > >         OEM Information: 0x00000000
> > >         Height: Unspecified
> > >         Number Of Power Cords: Unspecified
> > >         Contained Elements: 0
> > > <snip>
> > >
> > > post-pastch dmidecode:
> > > <snip>
> > > Handle 0x0001, DMI type 1, 27 bytes
> > > System Information
> > >         Manufacturer: socionext,developer-box
> > >         Product Name: Socionext Developer Box
> > >         Version: Unknown
> > >         Serial Number: Unknown
> > >         UUID: Not Settable
> > >         Wake-up Type: Reserved
> > >         SKU Number: Unknown
> > >         Family: Unknown
> > >
> > > Handle 0x0002, DMI type 2, 14 bytes
> > > Base Board Information
> > >         Manufacturer: socionext,developer-box
> > >         Product Name: Socionext Developer Box
> > >         Version: Unknown
> > >         Serial Number: Not Specified
> > >         Asset Tag: Unknown
> > >         Features:
> > >                 Board is a hosting board
> > >         Location In Chassis: Not Specified
> > >         Chassis Handle: 0x0000
> > >         Type: Motherboard
> > >
> > > Handle 0x0003, DMI type 3, 21 bytes
> > > Chassis Information
> > >         Manufacturer: socionext,developer-box
> > >         Type: Desktop
> > >         Lock: Not Present
> > >         Version: Not Specified
> > >         Serial Number: Not Specified
> > >         Asset Tag: Not Specified
> > >         Boot-up State: Safe
> > >         Power Supply State: Safe
> > >         Thermal State: Safe
> > >         Security Status: None
> > >         OEM Information: 0x00000000
> > >         Height: Unspecified
> > >         Number Of Power Cords: Unspecified
> > >         Contained Elements: 0
> > > <snip>
> > >
> > > Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> >
> > Reviewed-by: Peter Robinson <pbrobinson at gmail.com>
> > Tested-by: Peter Robinson <pbrobinson at gmail.com>
> >
> > > ---
> > >  lib/smbios.c | 41 +++++++++++++++++++++++++++++++++++++++--
> > >  1 file changed, 39 insertions(+), 2 deletions(-)
> 
> I've thought about this a lot.
> 
> As I mentioned earlier, we should require boards to add this
> information when they enable GENERATE_SMBIOS_TABLE
> 
> It is a simple patch for each board vendor and it solves the problem.
> What we have here just masks it.


Not entirely.  I think we just see the problem differently here.  I agree
that the code here masks a problem (but only for *some* boards) and ideally
we should go and add smbios nodes on the boards that miss it.  However we
conveniently keep ignoring OF_BOARD here.  Until those things are documented
in a spec and you can *demand* a previous bootloader to include it, we'll have
boards that display "Unknown" all over the place.   Personally I don't
think that's acceptable,  hence the last resort solution.

I'd be much happier if we popped a warning on boards that miss the smbios
node and are not compiling with OF_BOARD, explaining smbios will be
disabled for them in the future,  while having the flexibility to not
display values that make no sense.

Thanks
/Ilias

> 
> Regards,
> Simon