Re: [PATCH v1 2/4] x86/pci: Re-use new dmi_get_bios_year() helper

[Andy Shevchenko]

On Wed, 2018-02-28 at 20:21 +0100, Jean Delvare wrote:
> On Wed, 28 Feb 2018 11:33:39 +0100, Rafael J. Wysocki wrote:
> > On Wed, Feb 28, 2018 at 11:29 AM, Andy Shevchenko
> > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > I would assume that no BIOS date is related to prehistoric
> > > firmwares and
> > >  using _CRS would sound weird on them.  
> > 
> > Careful here.
> > 
> > You seem to be assuming that the DMI information is always valid
> > and/or complete which is know to not be the case sometimes.
> 
> True. While the BIOS date is not the worst offender when it comes to
> broken DMI data, you must remember that the date comes as a string,
> and
> older SMBIOS specifications did not even recommend a specific format
> for that string. As a matter of fact, my collection of DMI tables
> includes a few creative samples like "Jul  7 2016" or "09-16-08" which
> the kernel fails to parse.
> 
> So the default behavior at the driver level shouldn't be based on what
> older systems are most likely to enjoy. The default behavior must be
> the safest option, regardless of the age of the system.

Yep.

And here is a very good question which path is more safer: use _CRS, or
not?

Rafael, do you know any consequences of not using _CRS for PCI on older
and newer machines?

-- 
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy