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

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:

quoted

On Wed, Feb 28, 2018 at 11:29 AM, Andy Shevchenko
[off-list ref] wrote:

quoted

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 [off-list ref]
Intel Finland Oy