1 May
2014
1 May
'14
9:53 a.m.
Len Ovens wrote:
On Wed, 30 Apr 2014, Clemens Ladisch wrote:
Device 00:1c.3 is one of the PCIe ports of the southbridge.
Device 04:00 is the ASM1083 PCIe/PCI bridge.
Devices 05:xx are the chips on the PCI cards.
Bus 00: is the "root complex", i.e., CPU/northbridge/southbridge.
Bus 04: is the PCIe connection between the southbridge and the ASM1083.
Bus 05: is the PCI bus.
"[04-05]" means that both buses are reachable through this bridge.
Len Ovens wrote:
len@music:~$ lspci -t
-[0000:00]-+-00.0
+-01.0-[01]--
+-02.0
+-14.0
+-16.0
+-1a.0
+-1c.0-[02]--
+-1c.2-[03]----00.0
+-1c.3-[04-05]----00.0-[05]--+-00.0
| \-02.0
+-1d.0
+-1f.0
+-1f.2
\-1f.3
00:1c.3 would be the PCI bridge then as my two audio cards are listed
as 05:00.0 and 05:02.0. I would guess that the third PCI slot would be
01. I see that the bridge is listed as [04-05] I am guessing that
means 04 is the PCIe side and 05 is the PCI side? PCI bridge: Intel Corporation 8 Series/C220
Series Chipset Family PCI Express Root Port #3 (rev d5)
00:1c.3 PCI bridge: Intel Corporation 82801 PCI Bridge (rev d5)
I am not sure which is which. The first may be the express port.
The ASM1083 (which the manual says you have) should be listed as "ASM1083".
What is the output of "lspci -t"? So it sounds like you are saying that the PCIe devices
are assigned
an irq to be compatible with the PCI standard, but most PCIe devices
don't use the irq having another way to get the OS attention.
There are different kinds of interrupts. 0-15 are ISA-compatible
interrupts; the next four or eight can be used for PCI interrupts.
(The interrupt controller (IOAPIC) has only a limited number of
interrupt lines.)
Message-signaled interrupts (MSIs) are implemented with a different
mechanism and do not need to go through the IOAPIC; you can have any
number of them, and they are never shared between devices.
Looking at /proc/interrupts, I see that ahci (which
from lspci seems
to be the SATA controller) shows irq 42 even though the book says it
is sharing an irq with PCI slot 1 which has an ens1370 at irq 19. So
I would guess that this irq 42 is a "soft" irq?
Yes, it's an MSI.
(and why do I have an ISA bridge?)
Because you have ISA devices. (Intel likes to call them "legacy", but
they are still there.)
I would guess that if I installed a PCIe card that was
PCI HW with
a PCIe->PCI bridge on the card to update it, that it would still use
the old irq and could clash with one of my other PCI audio cards.
Yes.
Regards,
Clemens