From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2155) id AACF83858D39; Sat, 4 Nov 2023 09:57:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org AACF83858D39 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com; s=default; t=1699091835; bh=OJezt9hZZSJp0XR3PAkwASVMtJNI2CvcuNXZzEvgZIU=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=LlAGyXldypeQahQ2ImbL5Lix8tL6CALeuRri6QWTNUsyi1HQXlQPwX5S1QOYlZVnu 6dnawH2kRTAoe7PVaqQSG6oQuTP5raP2wRjSwWgzShWMdnCMJzeYYgDoHmggvQMJmP bfdvKihlDswppf0SEhyBz89QXm/60RPnJUTBvy0Q= Received: by calimero.vinschen.de (Postfix, from userid 500) id D0E56A807AC; Sat, 4 Nov 2023 10:57:13 +0100 (CET) Date: Sat, 4 Nov 2023 10:57:13 +0100 From: Corinna Vinschen To: Christian Franke Cc: cygwin-patches@cygwin.com Subject: Re: [PATCH] Cygwin: Add /dev/disk/by-id symlinks Message-ID: Reply-To: cygwin-patches@cygwin.com Mail-Followup-To: Christian Franke , cygwin-patches@cygwin.com References: <9fd70b83-2364-1e02-555f-dc7b24feff9c@t-online.de> <8ceefddf-6f66-ab44-f2fc-48072a5c7207@t-online.de> <1133d1d3-e6d9-4a52-a595-89ee338f8d2f@t-online.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: List-Id: On Nov 4 10:34, Corinna Vinschen wrote: > On Nov 3 18:54, Christian Franke wrote: > > 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 :-) > > Ok, but with the DUID we have a workaround which makes it work even > better than on Linux, so it would begreat if we used it, unless we find > out where the UUID in "\GLOBAL??\Disk{} comes from... > > Given the size of the STORAGE_DEVICE_UNIQUE_IDENTIFIER struct, we could > even contemplate a 128 bit hash, just to be on the safe side. Kind of like this - strcat (name, ioctl_buf + desc->SerialNumberOffset); + /* Use SerialNumber in the first place, if available */ + if (desc->SerialNumberOffset && desc_buf[desc->SerialNumberOffset]) + strcat (name, desc_buf + desc->SerialNumberOffset); + else /* Utilize the DUID as defined by MSDN to generate a hash */ + { + union { + unsigned __int128 all; + struct { + unsigned long high; + unsigned long low; + }; + } hash = { 0 }; + + for (ULONG i = 0; i < id->Size; ++i) + hash.all = ioctl_buf[i] + (hash.all << 6) + (hash.all << 16) - hash.all; + __small_sprintf (name + strlen (name), "%X%X", hash.high, hash.low); + } Corinna