No real support for multi-path targets (Bugzilla Bug 404)

[tianocore-issues]

This issue was created automatically with bugzilla2github

Bugzilla Bug 404

Date: 2017-02-23T17:18:03+00:00
From: mlazarow
To: Ye Ting <<ting.ye>>
CC: yonghong.zhu

Last updated: 2017-03-30T22:18:52+00:00

[tianocore-issues]

Comment 1510

Date: 2017-02-23 17:18:03 +0000
From: mlazarow

• Industry Specification: ---
• Releases to Fix: EDK II Master
• Target OS: ---
• Bugzilla Assignee(s): Ye Ting <<ting.ye>>

No documentation I can find is clear on multi-path boot devices and how to handle them.
Both fibre channel and iSCSI allow for 2 or more controllers in a system to connect to the same remote LUN. This results in some issues in relation to UEFI boots.

The first is in section 5.3.3 of the UEFI 2.6 specification which states the following:
"Software that makes copies of GPT-formatted disks and partitions must generate new Disk
GUID values in the GPT Headers and new Unique Partition GUID values in each GPT
Partition Entry. If GPT-cognizant software encounters two disks or partitions with identical GUIDs,
results will be indeterminate.”

While this concerns cloning a disk, 2 paths resulting in 2 instances of the block IO protocol that point to the same partition has effectively the same result.

The other issue is that it is desirable to be able to control the order the different paths are attempted. It does not appear the UEFI spec has a way for this to happen because of the short form device path used in a boot option.

This is a request to see the support for multi path boot targets be enhanced so the user can see each path as a separate boot option that can be ordered based on the path order they wish.

[tianocore-issues]

Comment 1518

Date: 2017-02-23 19:25:46 +0000
From: Yonghong Zhu <<yonghong.zhu>>

Bug scrub: Assign to module owner to take a look at first. if it is related with documenet, let Mike Rothman to take it to US TWG meeting to discuss.