Multiple Python inheritance in Gem5

[steven918]

It seems gem5 doesn't support multiple inheritance. For example

class QoSMEM(MemCtrl, QoSMemCtrl)

Would return "TypeErrro: SimObjects do not support multiple inheritance".

The reason I'm trying to have multiple inheritance is because there seems no direct way to instantiate QoSMemCtrl parameters from MemCtrl-derived class. For example,

class QoSMEM(MemCtrl):
def __init__(self):
super().__init__()
self.write_high_thresh_perc= "95" # OK, since write_high_thresh_perc is in MemCtrl
self.qos_policy = "fifo" # error because qos_policy is in QoSMemCtrl, even though MemCtrl is derived from QoSMemCtrl

How to assign parameters in such multiple level inheritance?

Thanks

[powerjg]

What is the error for self.qos_policy = "fifo"? That should work.

Maybe it expects an enum object instead of a string? (I haven't looked at the code)

[steven918]

The error message of that line when using class QoSMEM(MemCtrl) is:

TypeError: SimObject.init() takes 1 positional argument but 2 were given
Error setting param QoSMEM.qos_policy to fifo

I verified that a string like "fifo" works by inheriting directly from QoSMemCtrl, like this:
class QoSMEM(QosMemCtrl):
....
self.qos_policy = "fifo"

So that string part should be fine.