ExtScsiPassThru support for Logical SCSI devices

["Ravi Kumar Siadri" <siadriravikumaruefi@gmail.com>]

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Hi all,

I have couple of queries regarding the *EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_LOGICAL* attribute support in *EFI_EXT_SCSI_PASS_THRU_ PROTOCOL*.

*1.*
*The Attributes field of the EFI_EXT_SCSI_PASS_THRU_ PROTOCOL interface tells if the interface is for physical SCSI devices or logical SCSI devices. Drivers for non-RAID SCSI controllers will set both the EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_PHYSICAL, and the EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_LOGICAL bits.*

If the Drivers is for non-RAID SCSI controllers why to set the EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_LOGICAL bit. Will there be any case that non-RAID SCSI controllers have Logical devices connected to it ??
**
*2.*
*Drivers for RAID controllers that allow access to the physical devices and logical devices will produce two EFI_EXT_SCSI_PASS_THRU_ PROTOCOL interfaces:*
*One with the just the EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_PHYSICAL bit set and another with just the EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_LOGICAL bit set. One interface can be used to access the physical devices attached to the RAID controller, and the other can be used to access the logical devices attached to the RAID controller for its current configuration.*

Any background why EFI_EXT_SCSI_PASS_THRU_ PROTOCOL needed 2 instances ? why can't we install attributes EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_LOGICAL and EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_PHYSICAL on same Instance ??
How User locates the Instance with EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_LOGICAL bit set and Instance with EFI_EXT_SCSI_PASS_THRU_ ATTRIBUTES_PHYSICAL bit set. ??

Thanks,
Ravi Kumar

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