Comment 0 for bug 1817321

[Impact]

 * It's not possible to access iBFT (iSCSI Boot Firmware Table) information
   (settings for network interface, initiator, and target) in the installer
   because the 'iscsi_ibft' module is not present in udeb packages.

 * Even if it was, the installer does not handle iBFT information at all,
   thus any settings are ignored, and iSCSI-related configuration has to
   be done manually or with workarounds.

 * This impacts user-experience and automatic installation on systems and
   deployments which actually do provide the iBFT feature and information,
   but cannot use it practically.

 * With proper iBFT support in the installer (kernel module in udeb package
   and automatic iSCSI-related configuration) users will be able to rely on
   iBFT to install/deploy Ubuntu on their servers and datacenters.

 * These fixes add the 'iscsi_ibft' kernel module in the scsi-modules udeb,
   and configure network/iSCSI according to iBFT information in disk-detect.

   This is done in disk-detect so that the iSCSI LUNs are detected as disks
   (useful in case of no other disks in the system so the installer doesn't
   complain nor wait too long) and that any partman-related preseed options
   are not required and may be still available for the user.

[Test Case]

 * linux package / kernel module in udeb:

   $ dpkg-deb -c scsi-modules_*.udeb | grep iscsi_ibft.ko

   Check the module loads in the installer environment.
   See comment with example for disco.

 * d-i/hw-detect package:
   (to be done)

[Regression Potential]

 * linux package: low, the kernel module is not loaded by default,
   and only checks whether iBFT information is present in firmware,
   then exposes that in sysfs in read-only mode.

 * d-i/hw-detect:
   (to be done)

[Other Info]

 * This has been verified both by the developer with a simple iSCSI
   iBFT environment (2 VMs: iSCSI target & initiator with UEFI+iPXE)
   and by an user with system/firmware that supports iBFT for iSCSI.