Re: [PATCH] tools: usb: usbip: adding support for older kernel versions

From: shuah
Date: Mon Mar 25 2019 - 20:04:17 EST

On 3/25/19 5:02 PM, Brian Norris wrote:
On Mon, Mar 25, 2019 at 3:07 PM shuah <shuah@xxxxxxxxxx> wrote:
On 3/25/19 11:56 AM, Brian Norris wrote:
On Mon, Mar 25, 2019 at 8:51 AM shuah <shuah@xxxxxxxxxx> wrote:
In general the ABI is stable.

No, it really isn't. This commit was a breaking change:
But this one is definitely a break:

commit 1c9de5bf428612458427943b724bea51abde520a
Author: Yuyang Du <yuyang.du@xxxxxxxxx>
Date: Thu Jun 8 13:04:10 2017 +0800

usbip: vhci-hcd: Add USB3 SuperSpeed support

You can't just arbitrarily add columns to the beginning of a file like
that and claim that you're not breaking ABI. And I shouldn't need to
remind you that Thou Shalt Not Break User Space.

USB 3.0 driver and tool support went in, I would say it was oversight to
not make sure the tool continues to work on older kernels.

While that's true, you're still not grokking my main point when asking
about ABI stability:

*old* tools should still work on *new* kernels

The above commit broke that.

Agreed. Let's move forward with the assumption that this won't happen
in the future.

On a side note, in this specific tool case, the newer version is more
secure than the older version.

-- Shuah