hdparm bus state change failure

[Keith Lofstrom]

Around September 2004, the ability to hotswap IDE drives (in swap
trays) appeared in the redhat 2.4.ac kernels;  this ability was in
the release version of Fedora Core 1 with hdparm version 5.4. I
believe this capability was implemented by Alan Cox, correct me if
I am wrong.

With FC1 release, the sequence to hotswap drive hdg is:

unmount          /dev/hdg
hdparm    -b 0   /dev/hdg
                         (power off, change tray, power on)
hdparm   -zb 1   /dev/hdg
mount   /dev/hdg /mountpoint


With FC2 test 1, both with the as-distributed 2.6.1-1.65 kernel
and the updated 2.6.3-2.1.253 kernel, and version 5.5 hdparm,
the bus off command  * does not work *:

   [root]# hdparm -b 0 /dev/hdg
  
   /dev/hdg:
    setting bus state to 0 (off)
    HDIO_SET_BUSSTATE failed: Operation not supported
    busstate     =  1 (on)


FC1 works just fine on the very same hardware with a FC1 boot drive
swapped in.  It also works using the version 5.5 hdparm binary from
FC2T1 with the FC1 kernel.  Thus, the problem is in the FC2T1 kernel,
perhaps the hotswap mods did not get included or got broken.  

What should I test next, before I submit a bug to bugzilla? 

Keith

-- 
Keith Lofstrom           keithl at ieee.org         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs