Greg,
> So the timing as to when the parameters is not what I was addressing.
From your previous reply, it looked like you are not agreeing with my first statement
"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."
so this bootup time code involves all these sort of initialization, perhaps I used 'bootup time' as very abstract word. I think we are on same page.
BTW with your reply, looks you are also in storage domain.
Rajat
2010/11/6 Greg Freemyer <greg.freemyer@xxxxxxxxx>
2010/11/6 Rajat Sharma <fs.rajat@xxxxxxxxx>:
> Greg,Rajat,
> 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
>
The OP said "I am just exploring how much the linux is dependent on BIOS."
So the timing as to when the parameters is not what I was addressing.
I am saying that there are BIOS controlled parameters such as PCI ID
that impact linux in a fundamental way because they drive which ATA
driver is used.
Then further there are BIOS settings that are read by the kernel that
impact the operation of the drivers. That the parameters are only
read from the BIOS area on startup doesn't change the fact they impact
the operation during the entire time linux is running.
Note, while many BIOS parameters are used exclusively only for startup
hardware initialization, the ones I am referring to are used to
control the logic flow of the driver code in many routine operational
situations.
One simple example is for a fake-raid sata controller that implements
a meta-data area at the start of the disk in certain modes, but not
all. The linux driver for this must interrogate the system to
determine which mode the controller card is in and then set an
internal offset field to ensure that "sector 0" is what it is expected
to be.
If this is not done, then if the system is booted into Windows with a
dual-boot, the offsets will be wrong and everything falls apart in a
major way.
You might argue this is not a "BIOS" setting, but with many
motherboards today, the SATA controller is built in and the BIOS
directly controls which mode the controller operates in. Thus I would
call this a situation where "linux is dependent on BIOS".
Greg
