Oh, no, another 1100 jock ! Wow, those were great times. Indeed Sperry
distributed the OS source code to many, that’s why there were so many local
extensions at customer sites to accomodate special requirements. Believe it
or not, I could once write 1100 machine code, and Exec 8 was all written in
assembler.
I first worked with 1100s in 1970, the 1108 was it, not even the 1106
existed yet. The OS was still called Exec 8, and was never able to call it
anything else ! But I was mostly a communications guy in those times, and I
worked with DCPs a lot more than I worked with the 1100 proper. During the
mid-to-late seventies and even early eighties there was a lot of debate at
Sperry about the role of I/O vis-a-vis the trusted component of the
operating system, and I came to adopt one of the viewpoints of that time,
which is, I/O does not belong in the trusted kernel.
Also, I became fond of interrupt-less machines after working with the DCP
and previously having dabbled a bit on the 494, so, even today, I believe
that interrupts are for peripheral processors and not for the CPU.
Incidentally, I would very much like to put my hands on a 494 System
Description, I wonder if there’s any of those still available anywhere in
the planet ?
Alberto.
-----Original Message-----
From: David J. Craig [mailto:xxxxx@yoshimuni.com]
Sent: Tuesday, April 01, 2003 6:49 PM
To: NT Developers Interest List
Subject: [ntdev] Re: Mapping PCI registers for user app to use
Alberto, don’t you know yet that Microsoft and Bill Gates are the god of
computers and we must beg for anything we get? I realize maintaining
stability is their justification, but we can’t just call the HAL guy(s) and
get a new interface anytime we want to query or do something that wasn’t
exported. That is probably why Linux is becoming so popular and even IBM &
Sperry (I worked on the 1100/60/90 during the 1980’s) provided a lot of
source code for the OS, so if you needed to do something that wasn’t
possible with the code as written, you could modify the OS to provide the
service(s) you needed. Maybe if PC cost a few hundred thousand dollars was
could get this capability.
----- Original Message -----
From: “Moreira, Alberto”
To: “NT Developers Interest List”
Sent: Tuesday, April 01, 2003 6:15 PM
Subject: [ntdev] Re: Mapping PCI registers for user app to use
> Gary, it’s called a “spinlock”. It was invented well before either MSDOS
or
> Windows existed. In the hardware, it’s called a “test and set” or “compare
> and replace” instruction: back in the late sixties when I was a rookie,
> machines already had such instructions and SMPs were implemented on top of
> them, my very first industrial-strength system was the Univac 1108 and it
> had up to three shared memory processors. In fact, if you want an
efficient
> use of spinlocks, take a peek at http://lxr.linux.no and see for yourself
!
>
> Point being, the need to do multiprocessor synchronization doesn’t mean
that
> an application cannot or should not have access to I/O registers - it just
> means that the access must be synchronized, and that such synchronization
> should be exposed. Methinks the OS should expose that spinlock to the
> public, so that if we need to access PCI registers, we can do it without
> risking to leave the hardware in an inconsistent state.
>
> Alberto.
>
>
>
>
> -----Original Message-----
> From: Gary G. Little [mailto:xxxxx@aerosurf.net]
> Sent: Tuesday, April 01, 2003 5:50 PM
> To: NT Developers Interest List
> Subject: [ntdev] Re: Mapping PCI registers for user app to use
>
>
> NO Alberto, it is DOS-think … it is single threaded, single processing
> thinking … it is “Well I could do it that way in DOS!” or “DOS never
had
> that problem!” Here you go again preaching about what SHOULD be but isn’t
> and probably won’t be until you relase your own OS and the rest of us can
> then poke fun at how you did it. 
>
> Either in this thread or another one, I think Walter stated it fairly
> clearly that DSO-think is not ncessarily bad. If this is a proprietary
> system that will never ever see the inside of a Comp-USA, then go ahead
and
> use shared memory or ports in the users app, and do what ever is necessary
> to make it work with the realization that a lot of other things may quit
> working and you may have to do it all over again with the next release of
> Windows or SP. But please don’t sell it to the public.
>
> –
> Gary G. Little
> Have Computer, Will Travel …
> 909-698-3191
> 909-551-2105
> http://www.wd-3.com
>
> “Moreira, Alberto” wrote in message
> news:xxxxx@ntdev…
> >
> > The issue here isn’t “DOS think”, the issue here is the lack of a clean
> > synchronization mechanism to allow drivers to cleanly access PCI
> registers.
> > I consider this a glaring OS omission. And in a Pentium architecture,
> that’s
> > why we have segments, to create our own memory maps with protection
enough
> !
> > For example, it should be simple enough to create a segment that maps a
> > memory mirror of the PCI I/O space (maintained by a driver) and give it
> > read-only permissions so that the application can see what’s going on in
> > real time and asynchronously. There’s a ton of sophisticated hardware in
> > that machine, hey, use it !
> >
> >
> > Alberto.
> >
> >
> >
> >
> > -----Original Message-----
> > From: Gary G. Little [mailto:xxxxx@aerosurf.net]
> > Sent: Monday, March 31, 2003 8:23 PM
> > To: NT Developers Interest List
> > Subject: [ntdev] Re: Mapping PCI registers for user app to use
> >
> >
> > And just how do you expect to synchronize access to these PCI registers
> > between the user-mode app and any kind of kernel access? I will not even
> get
> > into cache line problems. I suppose you want to “read” data that was
> written
> > there in some kind of an asynchonous fashion with some kind of
asynchonous
> > signalling mechanism. Forget interrupts. You have no access to any
kernel
> > IRQL management functions such as spinlocks or the interrupt object
which
> > means that any time you attempt to read data or write data to these
> > “registers” it is essentially unsynchronized and very possibly corrupt.
> >
> > This is another example of DOS-think, and assuming that what one did in
> DOS
> > or that DOS-extender called 9x, you can do in NT and above. You can’t do
> it
> > that way without producing a highly unreliabel or snail slow system.
> >
> > –
> > Gary G. Little
> > Have Computer, Will Travel …
> > 909-698-3191
> > 909-551-2105
> > http://www.wd-3.com
> >
> > wrote in message news:xxxxx@ntdev…
> > >
> > > Hi,
> > >
> > > I am trying to map my PCI registers for use by a user application. I
do
> > > this by:
> > >
> > > In IRP_MJ_PNP, I call MmMapIoSpace to get a virtual address mapping
> > > (stored as VirtualAddress)
> > > In IRP_MJ_CREATE, I do:
> > > pDevExt->mdl = IoAllocateMdl( VirtualAddress,
> sizeof(ULONG)*307200,FALSE,
> > > FALSE, NULL );
> > > MmBuildMdlForNonPagedPool( pDevExt->mdl );
> > >
> > > In an IOCTL call, I do:
> > > MmMapLockedPages(pDevExt->mdl,UserMode) +
> > > MmGetMdlBytesOffset(pDevExt->mdl)
> > >
> > > In IRP_MJ_CLOSE, I do:
> > > MmUnmapLockedPages(VIrtualAddress,pDevExt->mdl)
> > > IoFreeMdl(pDevExt->mdl)
> > >
> > > The mdl is contained within my device extension and also
virtualaddress
> is
> > > in the device extension.
> > > When I run my user application, with just opening and closing the
handle
> > > to my driver for the FIRST time, it is fine. But as soon as I run it
> > > again, I get a BSOD with PAGE_FAULT.
> > >
> > > Am I doing the above correctly?
> > >
> > > I really appreciate any help I get.
> > >
> > > Thanks!
> > > Wynn
> > >
> > >
> >
> >
> >
> > —
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