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-   -   taking out CONFIG_IDE from kernel .config (http://www.linuxquestions.org/questions/slackware-14/taking-out-config_ide-from-kernel-config-695781/)

Yalla-One 01-08-2009 03:44 AM

taking out CONFIG_IDE from kernel .config
 
Hi,

I'm hoping someone familiar with the lower layers of IDE/SATA disk communications can kindly have a look at this.

Following a long discussion on lkml, I picked up that it's no longer recommended to keep the legacy IDE drivers in at the same time as the newer SATA drivers, so without changing anything else on my system, I removed CONFIG_IDE and friends.
It's the same 2.6.27.7 as I've always run - just took out IDE. See the link to the diff between the old .config and the new .config (without IDE) below.

I would have thought this would cause things to run more smoothly, but instead, I now find that the fan is now running almost all the time (not full-speed, but still audible) while earlier, it was almost always off.
Note that nothing else is changed. Same scaling governor, booting to runlevel 3, no binary blobs, no difference in application load. Just the fan running slightly more than with the legacy ide drivers compiled in.
So - while I thought I'd get things even more smoothly, I ended with the opposite.
Now - before someone jump in and say I should stick with the stock Slackware kernel - note that this is part of a learning expedition on my side to understand further of the kernel - I really want to understand this. I've read and read, and now I've hit a temporary obsticle, with which I would greatly appreciate some constructive input.
I suspect the problem lies in how the upper layers of disk access/filesystems communicate with the lower-level drivers sata / ide, but I haven't a clue as to why I see this behaviour...

Any insight or pointers to where this might be address would be greatly appreciated!

Diff showing what I took out of .config : http://pastebin.com/m5ac1d423

System is a Lenovo X200 with SATA hdd and cdrom. No functional difference in the system. boots and mounts hdd/cdrom just fine. Just the fan that's different.

And one small difference in dmesg post boot:
These lines obviously don't appear where I've taken out CONFIG_IDE:
Code:

Uniform Multi-Platform E-IDE driver
ide_generic: please use "probe_mask=0x3f" module parameter for probing all legacy ISA IDE ports
Probing IDE interface ide0...
Probing IDE interface ide1...


SiegeX 01-08-2009 08:57 PM

Rather than removing them entirely, you should have just used 'menuconfig' to uncheck the ones you didn't want. menuconfig categorizes the options and points to documentation (by pressing '?') to make sure that what you are removing is in fact solely IDE related. This would also make your diff a lot cleaner since it wouldn't be listing the removal of already commented out stuff.

Also, without loading up menuconfig to be sure, some of those options don't all seem to be related to IDE, such as

< CONFIG_SCSI_TGT=y
> CONFIG_SCSI_TGT=m
< CONFIG_CHR_DEV_ST=m

Yalla-One 01-08-2009 11:43 PM

Hi, and thanks for answering!

Quote:

Originally Posted by SiegeX (Post 3401770)
Rather than removing them entirely, you should have just used 'menuconfig' to uncheck the ones you didn't want.

This is exactly what I did. I never venture into entering .config by hand :-) I thought that was implied, sorry I didn't make it clearer in original post.

So I took out everything IDE and legacy-IDE-related from make menuconfig and then diffed the .configs when I didn't get the expected result...

The system works great, but the fan hums at low speed non-stop, as opposed to before...

Is there anything I should look for in /proc or /sys or elsewhere that might give a hint as to what's changed?


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