carrierlost

I think yes. If you have installed your windows 8.1 to MBR/legacy mode it should be the same as with windows 7. In case of UEFI/GPT I think install is possible, but configurarion/installation would needed to be modified (see phillofocs post for hints as he is using UEFI ).

Inspired by phillofocs writeup on linux+grub2+ASPM I managed to implement ASPM fix via grub2 without needing to install Linux on hard-drive or to re-install Windows 7. Starting situation So at the beginning I had standard Win7 installed which consumed the whole disk. Win7 creates 2 partitions by default - system (first) and the one you see as C: (second). I had no recovery partition. My setup was non-UEFI, so my setup uses the traditional bootup process and disk layout (MBR). The goal Grub2 installed on harddrive and configured so that it initializes the ASPM system and then starts (chainloads) the Windows. Steps 0. Make sure you have backup your important stuff in case you manage destroy something. 1. Reserve some space for grub2. Grub2 is going to need some small space to store its files and configuration data. I chose to create a very small partition for that. Firstly I needed to create some space on HDD for that.I shrunk Windows partition by 128M with built in Windows Disk Management tool. In the tool just right click on your C: partition and select Shrink Volume and select the amount to shrink. I used 128M, but you can get away with much less as my grub2 took less than 12Mbytes of that. You should now have some free space for grub. 2. Get some LIVE disc or usb stick of linux. We are not going to install the distro only to use to install grub2 once. I used lubuntu, 3. Boot to live linux from disc. Using you favorite partition tool (for example gparted) find that disk we created the free space on in step 1. Create a new partition. I used ext2 and make the filesystem on it. 4. Mount the filesystem somewhere and remember the mountpoint. I used /mnt/grub2 5. Important! We are about installing grub2 to MBR and to the newly created partition. Make sure you have time to troubleshoot this step if anything goes wrong. Once you have started you must complete it in order to have a bootable machine. 5a. Installing grub requires to run grub-install. Grub-install will install grub2 into HDD in two parts: first part will go to your MBR (/dev/sda) and second part to the partition we created (mounted on /mnt/grub2). Run sudo grub-install --root-directory=/mnt/grub2 /dev/sda Make sure that you use the right mountpoint if you used anything other than /mnt/grub2 in step 4. 5b, Go to /mnt/grub2. There should be directory boot under it and grub below it. Go there. It should have fonts, i386-pc, locale, grubenv. Now we need to create grub.cfg in that directory file that basically tells grub2 what to do at boottime. Without it would give you grub2 CLI at boot. set default=0 menuentry "Microsoft Windows 7 ASPM enabled" { ## Note: FACP address is 0xB9CF5xxx for bios F.34 ## FACP address is 0xB9FFCxxx for bios F.4x series write_byte 0xB9FFC06D 0x3 ## Now add 0x10 to checksum correct 0x10 deducted above to a unused byte write_byte 0xB9FFC019 0x10 chainloader (hd0,msdos1)+1 } menuentry "Microsoft Windows 7 standard" { chainloader (hd0,msdos1)+1 } set timeout=3 The configuration file creates a menu with two item. First (and default) which enables ASPM and boots Windows. Second just boots windows as before. You have 3 seconds to start making a selection, otherwise first choice is activated. Windows bootloader is assumed to be installed on partition1 (msdos1 in grub2 speak) of first hdd (hd0 in grub2 speak). Adjust if needed. Please note that bootoader resides in the System partition, NOT C:, (which is msdos2 in my case). I assume that you are running F.4x series BIOS (I'm using F.45). If not please adjust the memory writing addresses. Unmount /mnt/grub2. 6. Reboot and remove you live media. You should now have a menu where you can select whether to boot with ASPM or not. 7. Verify in windows that ASPM whether ASPM is enabled or not by using powercfg -energy Other notes: A. Feel free to change grub.cfg. You can reduce the timeout, rename the menuname etc. You can either do it by booting to linux and using an editor or mount it via ext2fsd in windows. B. UEFI based setup is possible, but will have to figure it out yourself. Look at writeup on linux+grub2+ASPM for clues. C. Why no setpci commands? Well I tested it and it made absolutely no added value on top of memory writes in my scenario (legacy boot process). In case UEFI it might be different. D. Can creating of grub2 partition avoided and grub2 files be located in some existing ntfs partition? Maybe. But grub2 is not exacly well documented and what we are doing here is already niche use-case. Please remember that if you decide to try this then I'm not going to be responsible if something breaks. Your HDD layout may be different based on how your windows is installed. Your linux distribution might be different. You might use UEFI. Grub2 version you are installing might be different. Dont attempt if you didnt understand the concepts described and you are able to correct for whatever circuimstances.