Hello,
On 08/31/17 22:45, Andrew A. wrote:
I tried the following to no avail:
setpci -s 00:14.0 0xd4.L=0x00000000
setpci -s 00:14.0 0xdc.L=0x00000000
This seems not to have taken hold upon readback:
setpci -s 00:14.0 0xd4.L
00003fff
setpci -s 00:14.0 0xdc.L
0000003f
This is also what I get on my machine.
(And indeed, the same problem persists -- qemu changes the port
mappings as soon as I boot a guest, locking me out of my host machine
until I ssh in and run 'setpci .. d0' again)
I took a look at what I believe is the R/WL property for these
settings, which is bit 31 of D20:F0:40h according to the datasheet,
so:
setpci -s 00:14.0 0x40.L
803609fd
sudo setpci -s 00:14.0 0x40.L=0x003609fd
Note that the ACCTRL bit is not documented in that register, further
suggesting that it is a BIOS-only control bit. Likely it is a write-once
bit, so once it has been set, it cannot be unset.
But this again didn't seem to have an effect:
setpci -s 00:14.0 0x40.L
803609fd
Note that other bits in the register can be changed (e.g. you can change
the 6 to a 0 to turn off power management, and change it back to a 6).
Just the top bit is write-protected.
Another potential problem is that your BIOS on the host may
write-protect the mask register. In that case, see the datasheet
for how to unlock it, if possible.
Right, and despite trying to remove the write protect I'm inclined
to think my unlocking commands are not working for some reason. Do
you see anything wrong with what I've tried here?
No, other than that it doesn't work :) I guess we're just out of luck
then, without doing something like patching your BIOS (so the bit never
gets set).
Thanks.
Regards,
Samuel
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