UDS Developments

[Kaj Ailomaa]

On 05/09/2012 11:02 AM, Ralf Mardorf wrote:
> On Tue, 2012-05-08 at 14:09 -0700, Scott Lavender wrote:
>
>>          "--"
>
> Please don't post under the signature lines ;).
>
>> my understanding is that the patch is what actually changes the config
>> file.  perhaps I am mistaken, however.
>
> It's likely that you're right, since
>
> spinymouse at precise:~$ grep
> PREEMPT /media/oz/boot/config-3.0.0-17-generic
> # CONFIG_PREEMPT_RCU is not set
> CONFIG_PREEMPT_NOTIFIERS=y
> # CONFIG_PREEMPT_NONE is not set
> CONFIG_PREEMPT_VOLUNTARY=y
> # CONFIG_PREEMPT is not set
>
> So to set CONFIG_PREEMPT will unset PREEMPT_VOLUNTARY and might do
> additional changes, e.g. it perhaps automatically will set PREEMPT_RCU.
>
> spinymouse at precise:~$ grep FORCE /media/oz/boot/config-3.0.0-17-generic
> CONFIG_IRQ_FORCED_THREADING=y
>
> Hm, already is set.
>
> spinymouse at precise:~$ grep HZ /media/oz/boot/config-3.0.0-17-generic
> CONFIG_RCU_FAST_NO_HZ=y
> CONFIG_NO_HZ=y
> # CONFIG_HZ_100 is not set
> CONFIG_HZ_250=y
> # CONFIG_HZ_300 is not set
> # CONFIG_HZ_1000 is not set
> CONFIG_HZ=250
> CONFIG_MACHZ_WDT=m
>
> So the second line for a two line config patch might be to set HZ_1000.
>
> For the same kernel source there might be a patch available that does
> set two options only for the config, than running oldconfig couldn't
> harm and it's ready to build the kernel.
>
> When I build 3.0.30 I used the config of 3.2.0-23-lowlatency and only
> echoed this by my build script:
>
> # Clean LOCALVERSION
>   grep CONFIG_LOCALVERSION .config
>   echo "CONFIG_LOCALVERSION=\"\"">>  .config
> # Optimize config
>   echo "CONFIG_MK8=y">>  .config
>   echo "CONFIG_DEBUG_KERNEL=n">>  .config
>   echo "CONFIG_NO_HZ=n">>  .config
>   make oldconfig
>
> IIRC there was no need to clean LOCALVERSION, MK8 for optimizing to my
> machine, IIRC DEBUG_KERNEL already is not set, so the echo also isn't
> needed, but NO_HZ was the only option that is set. I'll check this now:
>
> spinymouse at precise:~$ grep NO_HZ /boot/config-3.2.0-23-lowlatency
> # CONFIG_NO_HZ is not set
>
> I'm mistaken.
>
> So when building a new kernel, there's only the need to use the config
> of another lowlatency and to run oldconfig. No patch is needed, it's
> only needed for the config when using the config of a generic.
>
> - Ralf
>
>


Here's the address to the current git source 
git://kernel.ubuntu.com/themuso/ubuntu-precise-lowlatency