Bug 109731

Summary: dmi product_uuid is reported with incorrect endianness
Product: Drivers Reporter: Federico Simoncelli (federico.simoncelli)
Component: PlatformAssignee: Jean Delvare (jdelvare)
Status: RESOLVED CODE_FIX    
Severity: normal CC: jdelvare
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 4.2.7-300.fc23.x86_64 Subsystem:
Regression: No Bisected commit-id:

Description Federico Simoncelli 2015-12-21 13:42:36 UTC 
dmidecode and product_uuid are reporting the system uuid with different endianness:

  # dmidecode -s system-uuid
  3E001700-008E-3200-37B2-D46E0620D672

  cat /sys/class/dmi/id/product_uuid 
  0017003E-8E00-0032-37B2-D46E0620D672


I believe this behavior could be related to:

commit 95be58df74a5b21e5a78e45fddb2fd59112524c5
Author: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Date:   Wed Feb 18 13:33:20 2015 +0200

    firmware: dmi_scan: Use full dmi version for SMBIOS3

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=95be58df74a5b21e5a78e45fddb2fd59112524c5


Unless there's some specific reason to use a different endianness in product_uuid, it seems to me that the correct one is the one reported by dmidecode.

Also, with qemu instances:

  $ qemu-kvm -uuid 3E001700-008E-3200-37B2-D46E0620D672 ...

the correct one (same endianness) in the guest is the one reported by dmidecode.
Comment 1 Federico Simoncelli 2015-12-22 11:59:20 UTC 
My best guess at the moment is that the check modified in the patch mentioned above:

-	if (dmi_ver >= 0x0206)
+	if (dmi_ver >= 0x020600)

is not correct (it shouldn't have been necessary).
Comment 2 Federico Simoncelli 2015-12-28 09:06:08 UTC 
A fix has been proposed here:

https://lkml.org/lkml/2015/12/22/315