Greg, you are right about Intel AHCI, I also had to change it once in BIOS for detecting some Intel's SSD drives. But I think that was again for boot time hardware initialization. Are you sure that these parameters are accessed from BIOS routines on a running Linux kernel?
Rajat 2010/11/5 Greg Freemyer <[email protected]> > 2010/11/4 Rajat Sharma <[email protected]>: > > As I can remember, Linux uses BIOS only at the bootup time, after that on > a > > running kernel, there is no role of BIOS routines. Please refer to > > Understanding Linux Kernel for specific details. It also has one appendix > on > > Linux Boot-up sequence which depends on BIOS. Linux has its own drivers > for > > controlling IOAPIC and PCI drivers etc. > > Rajat > > Rajat, > > At least for the storage stack that is misleading because although > BIOS routines are not used, that does not mean the BIOS has no impact > on the kernel functionality. > > There are configuration choices made in the bios that have a > fundamental impact on the kernels operation: > > eg. > AHCI operation vs. Legacy > JBOD vs. fakeraid > etc. > > fundamentally impact how the hardware work and actually cause entirely > different ATA drivers to be used because these selections impact the > PCI-ID reported by the hardware. > > Then there are more detailed tuning parameters that are read by the > drivers to tune performance of the individual ATA drivers. For these > parameters, the storage drivers attempt to determine them on their > own, but in several scenarios the ATA controller is simply better able > to make an informed guess and the kernel simply reads those tuning > parameters and uses them. > > Greg >
