Bug 1967666

Hi,Peter, i have some questions for the issue?

1.How long the Unify length limits of serial number

2.What is the expected result if Serial number exceeding length? refuse to run or give a warning message?

3.How to handle the virtio device, (virtio-blk-pci), they should follow same rule of the serial number

Current test result:
1.create images
qemu-img create -f qcow2 /home/kvm_autotest_root/images/data1.qcow2 1G
qemu-img create -f qcow2 /home/kvm_autotest_root/images/data2.qcow2 2G
qemu-img create -f qcow2 /home/kvm_autotest_root/images/data3.qcow2 3G

2.boot vm with long serial number of data images

/usr/libexec/qemu-kvm \
  -name testvm \
  -machine q35 \
  -m 8G \
  -smp 8 \
  -cpu host,vmx,+kvm_pv_unhalt \
  -device qemu-xhci,id=usb1 \
  -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1 \
  \
  -device pcie-root-port,id=pcie-root-port-0,multifunction=on,bus=pcie.0,addr=0x3,chassis=1 \
  -device pcie-root-port,id=pcie-root-port-1,port=0x1,addr=0x3.0x1,bus=pcie.0,chassis=2 \
  -device pcie-root-port,id=pcie-root-port-2,port=0x2,addr=0x3.0x2,bus=pcie.0,chassis=3 \
  -device pcie-root-port,id=pcie-root-port-3,port=0x3,addr=0x3.0x3,bus=pcie.0,chassis=4 \
  -device pcie-root-port,id=pcie-root-port-4,port=0x4,addr=0x3.0x4,bus=pcie.0,chassis=5 \
  -device pcie-root-port,id=pcie-root-port-5,port=0x5,addr=0x3.0x5,bus=pcie.0,chassis=6 \
  -device pcie-root-port,id=pcie-root-port-6,port=0x6,addr=0x3.0x6,bus=pcie.0,chassis=7 \
  -device pcie-root-port,id=pcie-root-port-7,port=0x7,addr=0x3.0x7,bus=pcie.0,chassis=8  \
  -device virtio-scsi-pci,id=scsi0,bus=pcie-root-port-5 \
  -device virtio-scsi-pci,id=scsi1,bus=pcie-root-port-6 \
  -blockdev driver=qcow2,file.driver=file,cache.direct=off,cache.no-flush=on,file.filename=/home/kvm_autotest_root/images/rhel840-64-virtio-scsi.qcow2,node-name=drive_image1   \
  -device scsi-hd,id=os,drive=drive_image1,bus=scsi0.0,bootindex=0,serial=OS_DISK   \
  \
  -blockdev driver=qcow2,file.driver=file,file.filename=/home/kvm_autotest_root/images/data1.qcow2,node-name=data_image1   \
  -device scsi-hd,id=data1,drive=data_image1,bus=scsi0.0,bootindex=1,serial=0-1234567890-123456789-1234567890-abcdefg   \
  -blockdev driver=qcow2,file.driver=file,file.filename=/home/kvm_autotest_root/images/data2.qcow2,node-name=data_image2   \
  -device scsi-hd,id=data2,drive=data_image2,bus=scsi0.0,bootindex=2,device_id=1-1234567890-123456789-1234567890-abcdefg   \
  -blockdev driver=qcow2,file.driver=file,file.filename=/home/kvm_autotest_root/images/data3.qcow2,node-name=data_image3   \
  -device virtio-blk-pci,id=data3,drive=data_image3,bus=pcie-root-port-3,bootindex=3,serial=2-1234567890-123456789-1234567890-abcdefg   \
  -vnc :5 \
  -monitor stdio \
  -qmp tcp:0:5955,server=on,wait=off \
  -device virtio-net-pci,mac=9a:b5:b6:b1:b2:b7,id=idMmq1jH,vectors=4,netdev=idxgXAlm,bus=pcie-root-port-7 \
  -netdev tap,id=idxgXAlm \
  -chardev socket,id=qmp_id_qmpmonitor1,path=/var/tmp/monitor-qmp7.log,server=on,wait=off \
  -mon chardev=qmp_id_qmpmonitor1,mode=control \
  -chardev file,path=/var/tmp/monitor-serial7.log,id=serial_id_serial0 \
  -device isa-serial,chardev=serial_id_serial0 \
  -D debug.log \
  -boot menu=on,reboot-timeout=1000 \
   \

3.login guest

check vpd 

[root@localhost home]# lsblk -nd
sda    8:0    0  20G  0 disk 
sdb    8:16   0   1G  0 disk 
sdc    8:32   0   2G  0 disk 
vda  252:0    0   3G  0 disk 


[root@localhost home]# sg_vpd /dev/sdb --page=0x80;sg_vpd /dev/sdb --page=0x83
Unit serial number VPD page:
  Unit serial number: 0-1234567890-123456789-1234567890-ab
Device Identification VPD page:
  Addressed logical unit:
    designator type: vendor specific [0x0],  code set: ASCII
      vendor specific: 0-1234567890-1234567
[root@localhost home]# 
[root@localhost home]# 
[root@localhost home]# sg_vpd /dev/sdc --page=0x80;sg_vpd /dev/sdc --page=0x83
fetching VPD page failed: Numerical argument out of domain
sg_vpd failed: Numerical argument out of domain
Device Identification VPD page:
  Addressed logical unit:
    designator type: vendor specific [0x0],  code set: ASCII
      vendor specific: 1-1234567890-123456789-1234567890-abcdefg



[root@localhost home]# udevadm info /dev/sdb|grep ID_SERIAL
E: ID_SERIAL=0QEMU_QEMU_HARDDISK_0-1234567890-1234567
E: ID_SERIAL_SHORT=0-1234567890-1234567

[root@localhost home]# udevadm info /dev/sdc|grep ID_SERIAL
E: ID_SERIAL=0QEMU_QEMU_HARDDISK_1-1234567890-123456789-1234567890-abcdefg
E: ID_SERIAL_SHORT=1-1234567890-123456789-1234567890-abcdefg

[root@localhost home]# udevadm info /dev/vda|grep ID_SERIAL
E: ID_SERIAL=2-1234567890-1234567

(In reply to qing.wang from comment #1)
> Hi,Peter, i have some questions for the issue?
> 
> 1.How long the Unify length limits of serial number

For SCSI disks it should be unified to the technical limit of 248 characters, it doesn't make sense to pick arbitrary values.

> 2.What is the expected result if Serial number exceeding length? refuse to
> run or give a warning message?

Ideally qemu would reject startup or hotplug if the serial number can't be honoured. This is a question for 
https://bugzilla.redhat.com/show_bug.cgi?id=1967668

 
> 3.How to handle the virtio device, (virtio-blk-pci), they should follow same
> rule of the serial number

Unless there's a technical limit on the serial number lenght such as in case of IDE disks limiting it arbitrarily to 20 characters is wrong especially since at least some users want to use UUIDs which are 36 characters.

(In reply to Peter Krempa from comment #2)
> (In reply to qing.wang from comment #1)
> > Hi,Peter, i have some questions for the issue?
> > 
> > 1.How long the Unify length limits of serial number
> 
> For SCSI disks it should be unified to the technical limit of 248
> characters, it doesn't make sense to pick arbitrary values.
> 
> > 2.What is the expected result if Serial number exceeding length? refuse to
> > run or give a warning message?
> 
> Ideally qemu would reject startup or hotplug if the serial number can't be
> honoured. This is a question for 
> https://bugzilla.redhat.com/show_bug.cgi?id=1967668
> 
>  
> > 3.How to handle the virtio device, (virtio-blk-pci), they should follow same
> > rule of the serial number
> 
> Unless there's a technical limit on the serial number lenght such as in case
> of IDE disks limiting it arbitrarily to 20 characters is wrong especially
> since at least some users want to use UUIDs which are 36 characters.

yes, according to test in comment 1. so it will extent support 36 for virtio-blk-pci ?

(In reply to qing.wang from comment #3)
> (In reply to Peter Krempa from comment #2)
> > (In reply to qing.wang from comment #1)

[...]

> > > 3.How to handle the virtio device, (virtio-blk-pci), they should follow same
> > > rule of the serial number
> > 
> > Unless there's a technical limit on the serial number lenght such as in case
> > of IDE disks limiting it arbitrarily to 20 characters is wrong especially
> > since at least some users want to use UUIDs which are 36 characters.
> 
> yes, according to test in comment 1. so it will extent support 36 for
> virtio-blk-pci ?

The limit should not be arbitrary as the 36 characters for UUID in case of the SCSI disk was. Limits should be picked based on technical limits of the device interface.

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