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

[Mark Kettenis]

> From: Simon Glass <sjg at chromium.org>
> Date: Thu, 29 Sep 2022 17:55:43 -0600
> 
> Hi Ilias,
> 
> On Thu, 29 Sept 2022 at 04:23, Ilias Apalodimas
> <ilias.apalodimas at linaro.org> wrote:
> >
> > 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 think you mean OF_HAS_PRIOR_STAGE - we have an explicit Kconfig now.
> 
> We can easily make U-Boot halt if the info is not there but it is
> needed. That will cause people to fix it for their board.

That seems unecessarily harsh...

The smbios stuff is by no means essential to run an OS on a board.  On
many low-end (or user assembled) x86 machines it is full of lies as
well (gotta love all those machines with serial number 123456789) and
a lot of the information in the tables doesn't make sense for
"embedded" boards anyway.  At best the smbios tables are a "nice to
have" feature.  But it seems to be mostly a box ticking excercise to
me.

> > 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.
> 
> How about just failing the build and producing an error, if people
> enable the SMBIOS tables without the data? We could run with a warning
> for a while if you like, then change it to an error.

Again, that seems unecessarily harsh.  If foks are really bothered
about the correctness of the information we supply, we should either
just not offer the tables if essential information is missing from the
device tree, or maybe require boards to explicitly request the smbios
feature by dropping the "|| EFI_LOADER" from its Kconfig entry.