SoftFSB OCing 4 Linux (Dev)

[nando4]

Originally Posted by Darth_nVader

I can't seem to make that math work, but I'll plug at it for a while.

About Bootloaders, Grub2 can do basic PhysMem I/O RW, but SMBuses don't reside in this space, so to change Registers you'd need a driver for the SMBus + the Exc. Code.

Seems like a lot of work, when the Harddrive is what limits boot time, just not worth the extra 2 sec. you would gain, if you had highend raid or SSD.

I agree with the "additional 2 seconds" point, but the beauty of bootloader overclocking is it would be universal to all underlying operating systems, including ones where a tool like setfsb doesn't exist Eg: Leopard/DOS. Unless they have tools to do a SMBUS PLL write or do they?? I've asked the question about bootloader PLL overclocking on the grub2 mailing list. See what they have to say.

Additional update from abo on the calculation for FSB/byte13/byte14:

On Wed, Nov 4, 2009 at 2:53 PM, abo_setfsb wrote:

Hi Nando-san,

FSB = 14.318 * ((byte 13 & 0x40)<<3 + (byte 13 & 0x80)<<1 + byte 14)) / ((byte 13 & 0x3F) * CPU Div)
byte13= Hmm...
byte14= Hmm...

abo

[Darth_nVader]

If we look at lfsb, it has code for SMBus 2.0, but needs i2c-dev-> needs and SMBus driver like i2c_i801->they both need the linux kernel.

I don't think that it is reasonable or wise to try to gain access to the SMBus in a BootLoader, sure it can be done, however you turn your bootloader into a mini OS.

However, if you enumerate your SMBus as an ACPI device in the DSDT of your bios, you can then use ACPI code to R/W to your SMBus, but I believe this may limit to one off code for each Logic Board.

If we look past x86 Bios, EFI or OpenFirmware, these are Modular Mini OSes, that can Load and execute code from the HD, and with EFI it's C.

So, it's not really practical to try with GRUB, but could be done via ACPI and GRUB, I'm just not sure each Logic Board would not need it's own code.