SCSI Twin Channel Adapter addressing ???

SCSI Twin Channel Adapter addressing ???

Post by Jean-Pierre Radl » Mon, 27 May 1996 04:00:00



Quote:Heinz Wittenbecher writes:
> When using a twin channel adapter like the Adaptec 3940W how should the
> SCO5 kernel be configured for devices attached to Channel B?

> Channel A is straightforward, Adapter = 0, Bus = 0

> Channel B is where confusion sets in and all the scohelp hasn't helped
> to clarify it cut and dried (for me at least).

> Is Channel B considered Adapter 1, Bus 0 or Adapter 0, Bus 1

> or?

Adaptec 3940 SCSI adapter (dual channel) doesn't work when using a single IRQ.

KEYWORDS: adaptec 3940 openserver v5 5.0.0 aha dual channel scsi pci
controller alad ahs 5.1 alad325 different irq 2940 bus pci-to-pci bridging ppb
v2.0 compliant bios

RELEASE:  SCO OpenServer Enterprise System Release 5.0.0
          SCO OpenServer Desktop System Release 5.0.0
          SCO OpenServer Host System Release 5.0.0

PROBLEM:  I have an Adaptec 3940 Dual Channel SCSI PCI controller and want
          to use it for SCO OpenServer Release 5.

          I have attempted to configure this adapter to use the "alad" driver.
          When SCO OpenServer 5 is booted up, these driver messages are seen
          on the hardware screen:

                device    address       vector  dma     comment
                --------------------------------------------------------------
                ...
                %adapter  0xXXXX-0xXXXX 11      -   type=alad ha=0 id=7 fts=st
                %adapter  0xXXXX-0xXXXX 11      -   type=alad ha=1 id=7 fts=st
                ...

          Although the devices on channel A work fine, I cannot access any of
          the devices on channel B.

          I have tried three different alad drivers:

              - the one supplied in the basic SCO OpenServer 5 product
              - the one from the Advanced Hardware Supplement 5.1
              - the one supplied in the Adaptec package ("alad325")

          The symptoms of this problem are, however, the same when using each
          of these drivers.

CAUSE:    Although the Adaptec 3940 appears to be a dual channel card, it is
          actually two Adaptec 2940's on the same card, and therefore needs to
          be configured as two separate adapters with different Interrupt
          Request Queues (IRQs), rather than one adapter with two buses.

SOLUTION: Modify the machine's BIOS configuration for this adapter in order
          to configure it to use two different IRQs.  For example, use IRQ 11
          for the first PCI slot and IRQ 10 for the second (empty) PCI slot.

          After this change to the BIOS configuration, reboot the system,
          and these driver messages should now be displayed at the hardware
          screen:

                device    address       vector  dma     comment
                --------------------------------------------------------------
                ...
                %adapter  0xXXXX-0xXXXX 11      -   type=alad ha=0 id=7 fts=st
                %adapter  0xXXXX-0xXXXX 10      -   type=alad ha=1 id=7 fts=st
                ...

          It should now be possible to access all of the devices attached
          to channel B of this adapter, using any of the three alad drivers
          specified above.

NOTE:     The following hardware requirements are necessary when using the
          Adaptec 3940 Dual Channel SCSI PCI controller:

              - the system BIOS must support PCI-to-PCI bridging (PPB)
              - the machine's motherboard must be PCI v2.0-compliant

--

 
 
 

SCSI Twin Channel Adapter addressing ???

Post by Heinz Wittenbeche » Mon, 27 May 1996 04:00:00



> SOLUTION: Modify the machine's BIOS configuration for this adapter in order
>           to configure it to use two different IRQs.  For example, use IRQ 11
>           for the first PCI slot and IRQ 10 for the second (empty) PCI slot.

Thanks very much JP.

That explains why the 3940W picked up 2 IRQ's and my NIC picked the same IRQ as the
second Channel, as it was in the adjoining slot.

So much for saving a PCI slot, but we'll consider it a small price.

Thanks again for your quick reply.

Heinz


 
 
 

SCSI Twin Channel Adapter addressing ???

Post by Craig Macbri » Mon, 27 May 1996 04:00:00



>Adaptec 3940 SCSI adapter (dual channel) doesn't work when using a single IRQ.
>[ ... ]
>CAUSE:    Although the Adaptec 3940 appears to be a dual channel card, it is
>      actually two Adaptec 2940's on the same card, and therefore needs to
>      be configured as two separate adapters with different Interrupt
>      Request Queues (IRQs), rather than one adapter with two buses.

There seems to be something very wrong here. Isn't PCI supposed to be
able to share interrupts? The kernel can recognise that there are two
adapters at the same IRQ, so there should be a way to access both of
them. Or do users have to go back to EISA adapters for this to work
properly?

--

/      \        "I'm not sure that actually made sense but I'm afraid that
\_.--.*/        if I tried to go back and figure it out, I would start
      v         bleeding from my ears." - Londo, Babylon 5, "Convictions"

 
 
 

SCSI Twin Channel Adapter addressing ???

Post by Bill Campbe » Tue, 28 May 1996 04:00:00


......
: There seems to be something very wrong here. Isn't PCI supposed to be
: able to share interrupts? The kernel can recognise that there are two
: adapters at the same IRQ, so there should be a way to access both of
: them. Or do users have to go back to EISA adapters for this to work
: properly?

I've been told to set two 2942s to the same IRQ (11), and been doing
that for quite a while with no problems (other than the usual cable
sensitivity problems that the Adaptec 294x series seem to have).

Bill
--

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1. SCSI Twin Channel Adapter addressing ???

When using a twin channel adapter like the Adaptec 3940W how should the
SCO5 kernel be configured for devices attached to Channel B?

Channel A is straightforward, Adapter = 0, Bus = 0

Channel B is where confusion sets in and all the scohelp hasn't helped
to clarify it cut and dried (for me at least).

Is Channel B considered Adapter 1, Bus 0 or Adapter 0, Bus 1

or?

Thanks in advance -- Heinz

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