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I'm running Natty 64-bit on my Acer TimelineX 3820TG.This notebook has a switchable graphics card (ATI Radeon HD5650 and Intel Chipset).

Currently I am not using the fglrx drivers. I am a little confused as to how or which way to switch between the cards.

I have downloaded and compiled ACPI_Call and can load this with the following commands:

sudo insmod acpi_call.ko
test_off.sh

This works well for switching to the Intel Chipset and giving me about 7 hours of battery life (very sweet). However, that comes at a cost as I am not able to switch back to the ATI GPU (it causes my system to freeze and the only way to recover is REISUB), which is required if I want to put the laptop into sleep mode.

I recently read somewhere that switcheroo was actually made for the ATI/Intel cards so it raised a few questions for me which I hope someone can answer:

  • what is the difference between switcheroo and acpi_call?
  • What are the advantages/disadvantage of the two solutions?
  • How exactly do I use switcheroo on Natty? -- if it's built into the kernel, shouldn't it be automatic?
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I have used both on my 4820TG. Near as I can tell I go from 4.5 to 5 hours on battery with acpi_call to 4 hours with vga_switcheroo. Wifi on, basic web browsing stuff.

With vga_switcheroo suspend works whether the ATI is on or off. I do not use the ATI in linux at this time, just windows for gaming. However if I hibernate with the ATI off, when the machine awakens the ATI is on and cannot now be shut down without a reboot.

acpi_call simply results in a hang when suspending or hibernating.

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  • Assuming that switcheroo is just there on Natty you just do this: echo "OFF" > /sys/kernel/debug/vgaswitcheroo/switch
    – Scott Marlowe
    Jun 28, 2011 at 14:30
  • thanks for the feedback. So ACPI_Call would provide better battry life whilst switcheroo allows me to suspend while the intel card is on (but resuming in ATI). I've tried turning on switcheroo but I get this: sudo "OFF" > /sys/kernel/debug/vgaswitcheroo/switch bash: /sys/kernel/debug/vgaswitcheroo/switch: Permission denied
    – rimez
    Jun 30, 2011 at 5:20
  • The redirect works as you not root. Try echo "OFF"|sudo tee /sys/kernel/debug/vgaswitcheroo/switch
    – Scott Marlowe
    Jul 1, 2011 at 13:50

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