Re: [PATCH v1 0/4] Add command id quirk for fabrics

[Max Gurtovoy <mgurtovoy@nvidia.com>]

On 11/9/2021 6:15 PM, Keith Busch wrote:
> On Tue, Nov 09, 2021 at 03:31:02PM +0100, Christoph Hellwig wrote:
>> On Tue, Nov 09, 2021 at 04:23:33PM +0200, Max Gurtovoy wrote:
>>> On 11/9/2021 3:15 PM, Christoph Hellwig wrote:
>>>> Max, if you can't point us to a broken target (and yes, it is broken)
>>>> this will not go anywhere.
>>> Any target that uses Apple device as backend can be harmed.
>>>
>>> Most simple example is Linux PT target that copy the sqe as-is and passes
>>> it to the NVMe Apple drive.
>> Take another close look at how command_id are assigned my Linux driver.
>> We obviously do not pass it through as that would be completely broken.
> Also worth noting this driver has always defined the command id as a
> __u16, not __le16, yet we don't have any bug reports from big-endian
> hosts.

Right, my bad. I thought that the pass-through target uses the same id.

Linux PT target works fine.

Bad example.

Linux kernel world is covered but I still think we need to add this 
ability for fabrics controllers as we did for pci controllers.

There are a lot of vendors out there with their optimizations and 
solutions and by adding some code to cover a broken TCP target (that no 
one said what is this target and why nobody fixed it) by default that 
hurts others (even if it's spec compliant) is not a good practice.