Description of problem:
On my DELL Inspirion N4010 laptop, dmesg|grep i915 reported:

[   13.553483] [drm:i915_init] *ERROR* drm/i915 can't work without intel_agp module!
[   13.590076] intel ips 0000:00:1f.6: failed to get i915 symbols, graphics turbo disabled

dmesg|grep ips reported:

[   13.589917] intel ips 0000:00:1f.6: CPU TDP doesn't match expected value (found 25, expected 29)
[   13.589931] intel ips 0000:00:1f.6: PCI INT C -> GSI 18 (level, low) -> IRQ 18
[   13.590076] intel ips 0000:00:1f.6: failed to get i915 symbols, graphics turbo disabled
[   13.590770] intel ips 0000:00:1f.6: IPS driver initialized, MCP temp limit 90

I added intel-ips-dep-i915.conf file to /etc/modprobe.d:
   softdep intel_ips pre: i915

But it doesn't solve the issue.

In /boot/config-2.6.38.2-9.fc15.x86_64, the rules for intel_agp is:

   CONFIG_AGP=y
   CONFIG_AGP_AMD64=y
   CONFIG_AGP_INTEL=y
   CONFIG_AGP_SIS=y
   CONFIG_AGP_VIA=y

Once one kernel version for F15 I got i915 enabled, and glxgears performed 10xtimes fast than i915 disabled. But I don't rember that kernel version number.