Dear Ivan, dear Jeann,
There is an unwanted regression due to commit d7f96f97 (firmware:
dmi_scan: add SBMIOS entry and DMI tables).
Since Linux kernel 4.2 the utility `cbmem`, used to access information
stored in memory, from the coreboot project  does not work anymore
on a lot of systems as reported in corebootâs issue tracker as ticket
Failed to mmap /dev/mem: Resource temporarily unavailable
Aaron Durbin analyzed on the coreboot mailing list :
3) Why is that range set as uncached-minus? Would write-back work?
Please see this thread:
The actual issue stems from
which maintains a persistent mapping of smbios tables. It uses
dmi_remap() which is '#define dmi_remap ioremap' which is where the
uncached-minus PAT entry comes from. It should be using the same
mechanism as the ACPI table mappings which uses ioremap_cache().
Itâd be great, if the commit could be reverted, or the code be changed
in a way that `cbmem` still works.
If I should report this issue somewhere else, please tell me too, and
Iâll do my best to follow up there.