[ltp] How does /proc/acpi/ibm/bay work

[Tony Whitmore]

Greg Meyer wrote:
> On Thursday 31 March 2005 08:49 am, Theodore Ts'o wrote:
> 
>>On Thu, Mar 31, 2005 at 07:39:59AM +0200, Tino Keitel wrote:
>>>Hum, is there really nobody out there who uses UltraBay hotswapping?
>>
>>I can swap my DVD/CD-RW drive, as well as an additional IDE hard
>>drive.  In fact, I regularly use the hot-swap feature so that I can
>>disable the ultrabay when I am not using the disk, and when I am
>>suspending the laptop for additional power savings.
>>
>>This is on a T40, using the the following scripts.  The idectl script
>>is from the hdparm sources, in the contrib directory.
>>
>>					- Ted
> 
> I'll have to take a look at this again, but although I would like to use 
> hot-swapping in the ultrabay on my T41 between the combo dvd/cdrw and another 
> hard drive, I still haven't figured out a way to turn dma back on after the 
> swap.  A reboot has always been necessary to get dma back.

I have only had limited success with my R40. Having made the changes I 
suggested to Tino elsewhere in this thread, I was able to remove and 
re-insert the CD-RW/DVD drive. I am also able to remove and insert the 
battery in the ultrabay.

However, I can only get the device that was inserted on boot to be 
usable. So if I boot with the battery in, I can insert and remove it as 
often as I like. If I boot with the CD-RW drive, I can insert it and 
remove it as often as I like.

I disable DMA before removing the CD-RW drive and re-enable it 
afterwards. If I have booted with the CD-RW drive in and remove it, the 
LED on the Ultrabay doesn't light when I insert the battery. It may be 
that the BIOS is still using it as a power source, but I'm not sure. 
Removing the ACPI battery module and re-inserting doesn't detect the 
battery either.

If I boot with the battery in and try to insert the drive and reconnect 
the interface using "hdparm -R 0x170 0 0 /dev/hdc" I get "/dev/hdc: 
device not found" messages. (I use the command directly because idectl 
redirects output to /dev/null.)

One thing that is worth pointing out is that the ibm-acpi module doesn't 
detect my Ultrabay - the usual "bay not found" message is shown in 
dmesg. Yet on the ibm-acpi website, the bay is shown as "green" for the 
R40. Have any other R40 users had their Ultrabay detected by ibm-acpi?

Does anyone know a lack of support for a particular model's Ultrabay is 
just a case of the ibm-acpi software not yet supporting the bay in that 
model or a fundamental hardware issue that means it can never be supported?

Thanks,

Tony