Including header from separate driver tree make issues

alxhoff · 11-09-2018, 09:53 AM

Hi all,

I have been stuck on a problem for a couple of days now and am hoping someone can help me out.

I am looking into power management in the cpufreq module and need to get some stats from the GPU. I am developing the proof of concept for an Odroid XU3 board running a 3.10.9 kernel with a mali GPU. The stats I need can be exported from gpu_ipa.h. I am quite new to exporting symbols in the linux kernel so I hope what I am doing is actually the right approach.

My plan is to patch the midgard driver currently controlling the GPU to export the stats that are normally exposed via sysfs such that my cpufreq governor can access them. My first step was to try and get the gpu_ipa.h header included in my governor but I have since run into build errors.

I posted here but haven't had any luck.

From reading the documentation on the kernel build system it seems that what I should do is use a Kbuild file to build my module. Now I am not 100% sure, but I think because the kernel for this board is so old that the build system is a Kbuild/make mashup as my driver tree (cpufreq) doesn't have a Kbuild. I have tried making a Kbuild file in accordance to the documentation but have not had any luck. I have tried modifying the make file such that my module's entry looked like

Code:

ccflags-$(CONFIG_CPU_FREQ_GOV_OPTIGAME) := -I../gpu/arm/midgard 
obj-$(CONFIG_CPU_FREQ_GOV_OPTIGAME) += optigame_governor.o optigame_governor_sched.o optigame_governor_stats.o

I have never had do any modifying to Makefiles when i've developed kernel stuff and I am not sure my knowledge of make is good enough for a project as large as the kernel. I am begging for some help as this has really thrown a stopped on my research.

Cheers

Mara · 11-10-2018, 09:03 AM

For your module to compile, you need to have the CONFIG_CPU_FREQ_GOV_OPTIGAME option set to y or m in the kernel config. Have you added it to Kconfig?

alxhoff · 11-12-2018, 03:32 AM

I have an entry in the cpufreq Kconfig as follows

Code:

 config CPU_FREQ_GOV_OPTIGAME
     tristate "'optigame' cpufreq governor"
     depends on CPU_FREQ
     help
         'optigame' - optimized for games
 
         If in doubt, say N.

 config CPU_FREQ_DEFAULT_GOV_OPTIGAME
     bool "optigame"
     select CPUT_FREQ_GOV_OPTIGAME
     help
         User the CPUFreq governor 'optigame' as default

The module always built correctly prior to me wanting to add in the gpu integration. My problems have only started when I wanted to include the gpu_ipa.h header.