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Drive Interrupt button using Hercules?

 

Hello,

Many moon ago, I wrote programs to write CCW strings to various devices, including tape, DASD, CTCA, etc.

I remember having to run into the machine room and press the drive interrupt button.? Turns out from time to time my programs (during development) wrote CCW DASD strings that ended up in an infinite loop.? It was good to be the lead systems developer.? I'd catch these things quickly and handle them.??

I decided to move my mini-disks from the page and/or spool drvies.? For some reason the prior system developer felt the drives for those working to run the data center should be on the same drive as VM's drives.? I changed not only mine but everyone elses minidisks off of page, spool, etc drives.? I spread them across all controllers and channels.? Performance improved!

Bertram Moshier / WB8ERT
 

On Mon, Dec 19, 2022 at 04:57 PM, Bertram Moshier wrote:
I decided to move my mini-disks from the page and/or spool drvies.? For some reason the prior system developer felt the drives for those working to run the data center should be on the same drive as VM's drives.?
Maybe those DASD were on a daily/incremental backup schedule?

?... Mark S.
 

Huh?

This was real iron and occurred during my days of learning CCW programming.? (Habing programs write programs for me.)

So, how does one on Hercules interrupt a CCW program in an infinite loop?? On real iron I would press the 3350 (as an example) interrupt button.

Thanks.

On Fri, Dec 23, 2022, 09:43 Mark A. Stevens via <marXtevens=[email protected]> wrote:
On Mon, Dec 19, 2022 at 04:57 PM, Bertram Moshier wrote:
I decided to move my mini-disks from the page and/or spool drvies.? For some reason the prior system developer felt the drives for those working to run the data center should be on the same drive as VM's drives.?
Maybe those DASD were on a daily/incremental backup schedule?

?... Mark S.

 

On Fri, Dec 23, 2022 at 10:00 AM, Bertram Moshier wrote:
For some reason the prior system developer felt the drives for those working to run the data center should be on the same drive as VM's drives.?
As far as pushing buttons, IDK. I'm retired. I don't have any need to push anyone's buttons, nor to have mine pushed :-D

I was responding to why the developers files were on page/spool DASD. It's just a guess.
As a developer, I am concerned about backups of my stuff. As a Systems Programmer, I am concerned about performance.
It was lovely when I wore both hats. :-/

?... Mark S.
 

"So, how does one on Hercules interrupt a CCW program in an infinite loop?"

That would be the "I" (capital letter I) console command.

?I 0194

Joe

On Fri, Dec 23, 2022 at 10:00 AM Bertram Moshier <herc370390vm@...> wrote:
Huh?

This was real iron and occurred during my days of learning CCW programming.? (Habing programs write programs for me.)

So, how does one on Hercules interrupt a CCW program in an infinite loop?? On real iron I would press the 3350 (as an example) interrupt button.

Thanks.

On Fri, Dec 23, 2022, 09:43 Mark A. Stevens via <marXtevens=[email protected]> wrote:
On Mon, Dec 19, 2022 at 04:57 PM, Bertram Moshier wrote:
I decided to move my mini-disks from the page and/or spool drvies.? For some reason the prior system developer felt the drives for those working to run the data center should be on the same drive as VM's drives.?
Maybe those DASD were on a daily/incremental backup schedule?

?... Mark S.

 

Bertram Moshier wrote:

[...]
So, how does one on Hercules interrupt a CCW program in
an infinite loop? On real iron I would press the 3350
(as an example) interrupt button.
Hercules does not support any hardware-way of interrupting a device that is currently executing a channel program (Hercules does not support any type "interrupt" button of the device). The only hardware-way that I know of is via either re-initializing the device or detaching the device itself from, and then re-attaching it again to, your Hercules configuration (via either the 'devinit' or 'detach' and 'attach' commands). Of the two, doing a 'devinit' is probably the safest.

Detaching the device from, and then re-attaching it again to, your Hercules configuration is analogous to physically powering the device off and then powering it back on again, which, depending on what guest operating system you're running, could easily end up "boxing" the device.

Instead, the only recommended way that I am aware of is to actually cancel/abort the I/O itself via execution of either the Cancel Subchannel or Halt Subchannel instruction or the Halt I/O or Halt Device instruction.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

On Fri, 23 Dec 2022 at 11:29, Joe Monk <joemonk64@...> wrote:
"So, how does one on Hercules interrupt a CCW program in an infinite loop?"

That would be the "I" (capital letter I) console command.

?I 0194

I don't think so. That would just generate a standalone Device End (and/or Attention?). It's possible that might effectively interrupt a running channel program, but probably only because the OS will eventually issue a Halt I/O (or zArch equivalent) instruction.?

Tony H.
 

If I remember correctly, on the 3350? it was the attention button I pressed to generate the interrupt to break the CCW chain.

Thanks for the "I addr" command.

On Fri, Dec 23, 2022, 13:12 Tony Harminc <tharminc@...> wrote:
On Fri, 23 Dec 2022 at 11:29, Joe Monk <joemonk64@...> wrote:
"So, how does one on Hercules interrupt a CCW program in an infinite loop?"

That would be the "I" (capital letter I) console command.

?I 0194

I don't think so. That would just generate a standalone Device End (and/or Attention?). It's possible that might effectively interrupt a running channel program, but probably only because the OS will eventually issue a Halt I/O (or zArch equivalent) instruction.?

Tony H.
 

Tony Harminc wrote:
Joe Monk wrote:
Bertram Moshier wrote:

So, how does one on Hercules interrupt a CCW program in
an infinite loop?
That would be the "I" (capital letter I) console command.

I 0194
I don't think so. That would just generate a standalone Device
End (and/or Attention?).
Attention --- *IF* it were possible of course (which it's not because the device is still busy; you can only generate an attention interrupt for idle devices).

(And the command does NOT need to be capitalized either. A simple "i <devnum>" is all that is needed. It can be capitalized if you want to enter the command that way (I think), but it's certainly not necessary.)


It's possible that might effectively interrupt a running
channel program,
Nope. Not possible. Attention interrupts cannot be generated for devices that are still busy executing an I/O. Only idle devices can have an attention interrupt generated for them via the "i" command.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

Bertram Moshier wrote:

If I remember correctly, on the 3350 it was the attention button
I pressed to generate the interrupt to break the CCW chain.
We had 3350s at the shop I was at too, but I don't personally recall whether they had an attention button or not. Maybe they did, but we certainly never used it.

Now I do recall 3330s had a device address "plug" that you could "pop" (unplug and then plug back in again) and I do recall it being used once or twice, but it was an extremely rare occurrence and I don't recall under what circumstances it was used.

Thanks for the "I addr" command.
It's just "i" (lower case). It doesn't need to be capitalized unless you want to. BUT... it's not going to help you any in the situation you described (looping channel program) as it can ONLY be used on non-busy (i.e. idle) devices, and in the situation you described, the device would by definition always be busy.

I recommend using whatever guest O/S facility is available (if any) to cancel/abort the currently active I/O.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

Remember the discussion about MIH a while back?... :-)


On Fri, Dec 23, 2022 at 5:41 PM Fish Fish <david.b.trout@...> wrote:
Bertram Moshier wrote:

> If I remember correctly, on the 3350? it was the attention button
> I pressed to generate the interrupt to break the CCW chain.

We had 3350s at the shop I was at too, but I don't personally recall whether they had an attention button or not. Maybe they did, but we certainly never used it.

Now I do recall 3330s had a device address "plug" that you could "pop" (unplug and then plug back in again) and I do recall it being used once or twice, but it was an extremely rare occurrence and I don't recall under what circumstances it was used.

> Thanks for the "I addr" command.

It's just "i" (lower case). It doesn't need to be capitalized unless you want to. BUT... it's not going to help you any in the situation you described (looping channel program) as it can ONLY be used on non-busy (i.e. idle) devices, and in the situation you described, the device would by definition always be busy.

I recommend using whatever guest O/S facility is available (if any) to cancel/abort the currently active I/O.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...











--
Jay Maynard
 

If the I command won't cause the breaking of an active CCW for a device, what is the proper method for doing it?

I know with real iroon on a 3350 device, I was able to break an active CCW chain (in a loop).? Given (I thought Hercules reproduces real iron) what would be the equivalent?

Thank you.

On Fri, Dec 23, 2022, 17:33 Fish Fish <david.b.trout@...> wrote:
Tony Harminc wrote:
> Joe Monk wrote:
> > Bertram Moshier wrote:
> >
> > > So, how does one on Hercules interrupt a CCW program in
> > > an infinite loop?
> >
> > That would be the "I" (capital letter I) console command.
> >
> > I 0194
>
> I don't think so. That would just generate a standalone Device
> End (and/or Attention?).

Attention --- *IF* it were possible of course (which it's not because the device is still busy; you can only generate an attention interrupt for idle devices).

(And the command does NOT need to be capitalized either. A simple "i <devnum>" is all that is needed. It can be capitalized if you want to enter the command that way (I think), but it's certainly not necessary.)


> It's possible that might effectively interrupt a running
> channel program,

Nope. Not possible. Attention interrupts cannot be generated for devices that are still busy executing an I/O. Only idle devices can have an attention interrupt generated for them via the "i" command.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

Bertram Moshier wrote:

If the I command won't cause the breaking of an active CCW
for a device, what is the proper method for doing it?
As I wrote earlier, via execution of either the Cancel Subchannel or Halt Subchannel instruction or the Halt I/O or Halt Device instruction.


I know with real iron on a 3350 device, I was able to break
an active CCW chain (in a loop). Given (I thought Hercules
reproduces real iron)
As best it can, yes. But unfortunately not every feature that supported devices had are necessarily emulated (supported) in Hercules. Our device emulation support is mostly limited to just the programmatic variety, i.e. the various CCW opcodes that the device supported. But even then we don't necessarily fully support ALL of them. Just the most of the most popular ones.

what would be the equivalent?
There is no equivalent unfortunately (AFAIK). Sorry! :(

Is there a reason you can't just cancel/abort your I/O via the guest operating system? Why is having this button so important?

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 


The 3350 manual says:

When pressed, the Attention pushbutton starts a Rezero operation. Rezero moves the heads to cylinder zero, resets the address registers, and signals Attention to the controller.

Joe



On Fri, Dec 23, 2022 at 6:45 PM Bertram Moshier <herc370390vm@...> wrote:
If the I command won't cause the breaking of an active CCW for a device, what is the proper method for doing it?

I know with real iroon on a 3350 device, I was able to break an active CCW chain (in a loop).? Given (I thought Hercules reproduces real iron) what would be the equivalent?

Thank you.

On Fri, Dec 23, 2022, 17:33 Fish Fish <david.b.trout@...> wrote:
Tony Harminc wrote:
> Joe Monk wrote:
> > Bertram Moshier wrote:
> >
> > > So, how does one on Hercules interrupt a CCW program in
> > > an infinite loop?
> >
> > That would be the "I" (capital letter I) console command.
> >
> > I 0194
>
> I don't think so. That would just generate a standalone Device
> End (and/or Attention?).

Attention --- *IF* it were possible of course (which it's not because the device is still busy; you can only generate an attention interrupt for idle devices).

(And the command does NOT need to be capitalized either. A simple "i <devnum>" is all that is needed. It can be capitalized if you want to enter the command that way (I think), but it's certainly not necessary.)


> It's possible that might effectively interrupt a running
> channel program,

Nope. Not possible. Attention interrupts cannot be generated for devices that are still busy executing an I/O. Only idle devices can have an attention interrupt generated for them via the "i" command.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

OK, so what does the 3830 do with that? Or the 3880?


On Fri, Dec 23, 2022 at 7:44 PM Joe Monk <joemonk64@...> wrote:

The 3350 manual says:

When pressed, the Attention pushbutton starts a Rezero operation. Rezero moves the heads to cylinder zero, resets the address registers, and signals Attention to the controller.

Joe



On Fri, Dec 23, 2022 at 6:45 PM Bertram Moshier <herc370390vm@...> wrote:
If the I command won't cause the breaking of an active CCW for a device, what is the proper method for doing it?

I know with real iroon on a 3350 device, I was able to break an active CCW chain (in a loop).? Given (I thought Hercules reproduces real iron) what would be the equivalent?

Thank you.

On Fri, Dec 23, 2022, 17:33 Fish Fish <david.b.trout@...> wrote:
Tony Harminc wrote:
> Joe Monk wrote:
> > Bertram Moshier wrote:
> >
> > > So, how does one on Hercules interrupt a CCW program in
> > > an infinite loop?
> >
> > That would be the "I" (capital letter I) console command.
> >
> > I 0194
>
> I don't think so. That would just generate a standalone Device
> End (and/or Attention?).

Attention --- *IF* it were possible of course (which it's not because the device is still busy; you can only generate an attention interrupt for idle devices).

(And the command does NOT need to be capitalized either. A simple "i <devnum>" is all that is needed. It can be capitalized if you want to enter the command that way (I think), but it's certainly not necessary.)


> It's possible that might effectively interrupt a running
> channel program,

Nope. Not possible. Attention interrupts cannot be generated for devices that are still busy executing an I/O. Only idle devices can have an attention interrupt generated for them via the "i" command.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...











--
Jay Maynard
 

Well , I would think you would get DE out of it , and maybe CE? as well as I/O interrupt.

Joe

On Fri, Dec 23, 2022 at 7:47 PM Jay Maynard <jaymaynard@...> wrote:
OK, so what does the 3830 do with that? Or the 3880?

On Fri, Dec 23, 2022 at 7:44 PM Joe Monk <joemonk64@...> wrote:

The 3350 manual says:

When pressed, the Attention pushbutton starts a Rezero operation. Rezero moves the heads to cylinder zero, resets the address registers, and signals Attention to the controller.

Joe



On Fri, Dec 23, 2022 at 6:45 PM Bertram Moshier <herc370390vm@...> wrote:
If the I command won't cause the breaking of an active CCW for a device, what is the proper method for doing it?

I know with real iroon on a 3350 device, I was able to break an active CCW chain (in a loop).? Given (I thought Hercules reproduces real iron) what would be the equivalent?

Thank you.

On Fri, Dec 23, 2022, 17:33 Fish Fish <david.b.trout@...> wrote:
Tony Harminc wrote:
> Joe Monk wrote:
> > Bertram Moshier wrote:
> >
> > > So, how does one on Hercules interrupt a CCW program in
> > > an infinite loop?
> >
> > That would be the "I" (capital letter I) console command.
> >
> > I 0194
>
> I don't think so. That would just generate a standalone Device
> End (and/or Attention?).

Attention --- *IF* it were possible of course (which it's not because the device is still busy; you can only generate an attention interrupt for idle devices).

(And the command does NOT need to be capitalized either. A simple "i <devnum>" is all that is needed. It can be capitalized if you want to enter the command that way (I think), but it's certainly not necessary.)


> It's possible that might effectively interrupt a running
> channel program,

Nope. Not possible. Attention interrupts cannot be generated for devices that are still busy executing an I/O. Only idle devices can have an attention interrupt generated for them via the "i" command.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...











--
Jay Maynard

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