About AHCI BAR[5]

[zgxltxz]

Hello,
My English is poor.
I'm researching AHCI operation. About ABAR (BAR [5]), after reading a value of 0 x00003091, Why BA is 0?

Code: Select all

mov eax,10000000000000001111101000011000b
mov dx,0cf8h
out dx,eax
mov dx,0cfch
in eax,dx

after,EAX=0x00003091

[Shaun]

as far as i can know, your busno = 0x0, devno = 0x1f, func=0x02, reg = 0x06, first, are you sure these registers you specified are correct?

also, abar 5 address offset in pci configuration space for ahci is 0x24, but your reg is 0x06?

[Combuster]

00011000b

reg = 0x06

The offset used here is actually 24 decimal, or the 6th doubleword - mixing up these units is a typical beginner error.

In reality, to get BAR5 the offset should be 0x24 hexadecimal rather than decimal.

[zgxltxz]

as far as i can know, your busno = 0x0, devno = 0x1f, func=0x02, reg = 0x06, first, are you sure these registers you specified are correct?

also, abar 5 address offset in pci configuration space for ahci is 0x24, but your reg is 0x06?

oh,I always thought 4 bytes per register.Thank you for your answer !

[zgxltxz]

00011000b

reg = 0x06

The offset used here is actually 24 decimal, or the 6th doubleword - mixing up these units is a typical beginner error.

In reality, to get BAR5 the offset should be 0x24 hexadecimal rather than decimal.

thank you,I realized the mistake.