Re: [PATCH] Cygwin: Add /dev/disk/by-id symlinks

[Christian Franke <Christian.Franke@t-online.de>]

Corinna Vinschen wrote:
> On Nov  3 17:27, Corinna Vinschen wrote:
>> On Nov  3 17:09, Christian Franke wrote:
>>> Unlike (S)ATA and NVMe, the serial number
>>> is not available for free in the device identify data block but requires an
>>> extra command (SCSI INQUIRY of VPD page 0x80). This might not be supported
>>> by the emulated controller or Windows does not use this command.
>> AFAICS, only the data from STORAGE_DEVICE_ID_DESCRIPTOR is available
>> which is equivalent to the data from VPD page 0x83.  As you can see,
>> it's part of the STORAGE_DEVICE_UNIQUE_IDENTIFIER data.  The data
>> returned for the VirtIo device is the identifier string "\x01\x00",
>> which is a bit underwhelming.
>>
>> Would be great if we would learn how to access page 0x80...
> Uhm...
>
> MSDN claims:
>
>    If the storage device is SCSI-compliant, the port driver attempts to
>    extract the serial number from the optional Unit Serial Number page
>    (page 0x80) of the VPD.
>
> Now I'm puzzled.

A quick test with a Debian 12 VM in VirtualBox with many virtual 
controllers+drives shows the same problem:
Entries in /dev/disk/by-id appear only for virtual disks behind emulated 
SATA and NVMe controllers, but not for SCSI and SAS controllers.
A test with "smartctl -i ..." with SCSI/SAS devices doesn't print a 
serial number. In debug mode it prints "Vital Product Data (VPD) INQUIRY 
failed..." and other messages that suggest limited/buggy support of 
optional SCSI commands.

If a Win11 PE (from install ISO) is run in same VM, the 
STORAGE_DEVICE_DESCRIPTOR only provides the serial number for SATA (NVMe 
drives not detected), but not for SCSI.

Conclusion: The behavior of the current patch is compatible with Linux :-)

Christian