On Sun, Aug 14, 2016 at 03:26:45AM -0700, David Lang wrote:

On Sun, 14 Aug 2016, Tom Yan wrote:

quoted

On 14 August 2016 at 18:07, Tom Yan [off-list ref] wrote:

quoted

On 14 August 2016 at 18:01, Pavel Machek [off-list ref] wrote:

quoted

Since SATA support was merged, certainly since v2.4, and from way
before /dev/disk/by-id existed.

I have no idea how "SATA before USB" had been done in the past (if it
was ever a thing in the kernel), but that has not been the case since
at least v3.0 AFAIR.

quoted

People may not run udev, and you can't use /dev/disk/by-id on kernel
command line.

No, but you can always use root=PARTUUID=, that's built into the
kernel. (root=UUID= requires udev or so though).

Silly me. root=UUID= has nothing to do with udev, but `blkid` in
util-linux. At least that's how it's done in Arch/mkinitcpio.

The rule is "don't break working systems", not "but we are allowed to break
systems, see it says here not to depend on this"

Drive ordering has been stable since the 0.1 kernel [1]

Drive probing order of USB has always been non-deterministic, so while I
agree that it is not good to break existing systems at all, perhaps this
is on the edge of what works vs. doesn't work?

I know my USB drives always seem to come up in random order, which is
why tools like udev were invented :)

It takes a lot longer to detect USB drives, why in the world would they be
detected before hard-wired drives?

Depends, some hard-wired drives take much longer to find than USB ones.

That being said, it would be great if the original reporter could use
'git bisect' and let the linux-usb and linux-scsi mailing list know what
the offending patch is, and we can take it from there.

thanks,

greg k-h
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