IRQ 2 problem

[John Baldwin]

On 01-Jan-2004 M. Warner Losh wrote:
> In message: <1072952198.3233.24.camel at herring.nlsystems.com>
>             Doug Rabson <dfr at nlsystems.com> writes:
>: On Wed, 2003-12-31 at 20:25, M. Warner Losh wrote:
>: > In message: <XFMail.20031231141216.jhb at FreeBSD.org>
>: >             John Baldwin <jhb at FreeBSD.org> writes:
>: > : 
>: > : On 31-Dec-2003 Rostislav Krasny wrote:
>: > : > --- "M. Warner Losh" <imp at bsdimp.com> wrote:
>: > : >> In message: <20031230.190927.108191769.imp at bsdimp.com>
>: > : >>             "M. Warner Losh" <imp at bsdimp.com> writes:
>: > : >> : The reason that it iasn't been committed is because it is
>: > : >> incorrect.
>: > : >> : 
>: > : >> :
>: > : >>
>: > : > http://docs.freebsd.org/cgi/getmsg.cgi?fetch=15473+0+archive/2003/freebsd-arch/20030831.fre
>: > : > ebsd-ar
>: > : > ch
>: > : >> : 
>: > : >> : has the particulars.
>: > : >> 
>: > : >> Does your machine have an APIC?  My laptop doesn't seem to exhibit
>: > : >> the problem.
>: > : > 
>: > : > No, it doesn't seem to have an APIC. This is Pentium MMX 200MHz machine
>: > : > based on Intel's 430TX chipset.
>: > : > 
>: > : > What is the correct way to fix this IRQ 2 problem? I can help to test it.
>: > : 
>: > : IRQ 2 in FreeBSD is spelled IRQ 9.  If a PNP device wants to use IRQ 2, it
>: > : can be set to IRQ 2 in hardware, but it must use IRQ 9 when doing the
>: > : bus_alloc_resource() and bus_setup_intr().
>: > 
>: > Actually the problem appears to be that the hardware wants 9 too.  '2'
>: > shouldn't be used at all, nor given out in allocation when we're using
>: > AT PIC because that's the chaining IRQ.  That's the current problem.
>: > Eg, the isa bus is handing out '2' when it has no buisness doing so.
>: 
>: The original fix for this which has been lost over the years was to
>: exclude IRQ2 from the set of available interrupts. When the PnP code
>: attempted to allocate an irq for the device, it would try for 2, not get
>: it and settle for 9.
>: 
>: At some point, IRQ2 was added back into the set but the PIC driver was
>: fixed to allocate IRQ2 itself as early as possible. This matches the way
>: the hardware is wired together and has a certain 'rightness' to it.
>: Unfortunately the PIC driver doesn't seem to allocate IRQ2 for itself
>: any more which makes it available for broken PnP devices.
> 
> It looks like IRQ2 isn't registered as an interrupt source, so when we
> create the resource map, it looks like we skip it and shouldn't be
> handing it out...

Yes, it doesn't exist as a valid IRQ in the irq map anymore.  Oh, but you
know what, the resource manager is really buggy in this respect.  For example,
on my system here:

Interrupt request lines:
    0x0 (root0)
    0x1 (atkbd0)
    0x2 (root0)
    0x3 (sio1)
    0x4 (sio0)
    0x5-0x8 (root0)
    0x9 (acpi0)
    0xa-0xb (root0)
    0xc (psm0)
    0xd (npx0)
    0xe (ata0)
    0xf (ata1)
    0x10 (uhci0)
    0x11 (sis0)
    0x12 (uhci2)
    0x13 (uhci1)
    0x14 (fxp0)
    0x15-0x17 (root0)

Note that the nexus didn't add IRQ 2 as a possible resource, but the
resource manager went ahead and added it anyway when the adjacent
regions were added.  Someone should fix the resource manager code
perhaps.

-- 

John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/