[ltp] Re: Applying undervolting patches

[David Abrahams]

Andrew Barr <andrew.james.barr@gmail.com> writes:

> On Wed, 2006-08-23 at 07:29 -0400, David Abrahams wrote:
>> Andrew Barr <andrew.james.barr@gmail.com> writes:
>> 
>> > Hardware disappearing is because you don't have a driver for it. 
>> 
>> Something suddenly ripped the ipw3945 driver that comes with ubuntu
>> out of my stock kernel?
>
> The ipw3945 driver is not in mainline yet. 

I know that, but it is shipped as part of ubuntu's kernel.

> You need to get it from http://ipw3945.sourceforge.net/ and compile
> it for your stock kernel.

Somewhere we're not communicating.  Let me try again:

* When I say "stock," I mean "stock ubuntu dapper" -- the prebuilt
  kernel that ubuntu installs by default and upgrades as necessary
  from their repository.

* My card used to work with that kernel, and ubuntu includes the
  ipw3945 driver in its kernel.

* I did not replace my stock kernel when I built a kernel with the
  linux-phc patches.  The stock kernel is still present on my machine.

* Now when I boot into the stock kernel, the wireless card is not
  present.

* Are you saying that building the patched kernel and/or booting into
  it somehow managed to remove the driver from my stock kernel?  How
  is that possible?

>> > You need to find out what the driver is that your wireless card uses
>> > and recompile it for the new kernel (or enable in the configuration
>> > it if it is in-tree).
>> 
>> Yeah, but why is it gone for the old kernel?
>
> If the kernel version strings are the same (output of 'uname -r') 

My patched kernel is called 2.6.15.7-ubuntu1-phc.  My stock kernel is
2.6.15-26-686.

> then perhaps the module directories are clobbering each other. It's
> also possible that the ipw3945 build system (if you are compiling it
> yourself) 

I didn't try to build it for the patched kernel.

> is being too smart for its own good and deleting any old
> ipw3945.ko files it finds.

/lib/modules/2.6.15-26-686/kernel/drivers/net/wireless/ipw3945/ipw3945.ko
is present.

For that matter, so is
/lib/modules/2.6.15.7-ubuntu1-phc/kernel/drivers/net/wireless/ipw3945/ipw3945.ko

>> > I don't know about the ATI driver. Out of tree modules, proprietary or
>> > not, that use kernel APIs extensively (like device drivers) tend to
>> > break between kernel versions easily. Many times looking at communities
>> > (forums, mailing lists, wikis) that have a large number of users of a
>> > particular third-party module will have a patch to update them for new
>> > kernel versions.
>> 
>> At the moment I'm using the same kernel version with just a few minor
>> patches.  The question is why it stops working in one kernel when I
>> install it for the other kernel.  Don't they have separate modules
>> directories?
>
> This is an issue with the ATI driver specifically. You'll have to ask
> the ATI mailing list/web forum/whatever for help there. I've been
> bedeviled by a similar issue trying to upgrade my home theater PC box to
> 2.6.17. It uses the proprietary nVidia display driver.

OK, I'll ask someone.  I don't know if they have a forum, exactly, but
I have an internal contact.

> These drivers and their components (GL libraries, DDX drivers, kernel
> modules) are packaged as a unit and rather fragile. If you change
> something out from under them they tend to break.

Noticed :)

>> Seen that, but none for my CPU.  I took mine from NHC.  Although I
>> can't be 100% sure I know what those frequency scaling factors 6, 7,
>>  ...13 NHC uses are, I just assumed that 13 was 100% of the rated speed
>> and scaled down linearly from there.  NHC seems to have 8 steps while
>> linux-phc only seems to recognize 4.  Not sure what that means.
>
> Windows, I think, uses the "throttling" feature of your processor to
> drive the clock speed down even more. 

Ah.

> This is, from what I've seen on
> the linux-acpi mailing list, a questionable move because it carries
> minimal or no power-saving benefits.

Noticed that too.

> I saw Windows take an older laptop I had down to 200 MHz where the
> cpufreq driver only went down to 600 MHz.

I'm not sure why, but it seems like linux-phc isn't working for me
yet.  Maybe it has to do with taking the wrong numbers from NHC based
on throttling:
https://www.dedigentoo.org/pipermail/linux-phc-user/2006-August/000010.html
https://www.dedigentoo.org/pipermail/linux-phc-user/2006-August/000010.html

Thanks for your time and attention,

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com