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Something like a KVM switch for multiple Raspberry Pis

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  Something like a KVM switch for multiple Raspberry Pis "James Harris" <james.harris.1@gmail.com> - 2015-09-06 18:00 +0100
    Re: Something like a KVM switch for multiple Raspberry Pis Dave Higton <dave@davehigton.me.uk> - 2015-09-06 21:46 +0100
      Re: Something like a KVM switch for multiple Raspberry Pis "James Harris" <james.harris.1@gmail.com> - 2015-09-07 17:42 +0100
    Re: Something like a KVM switch for multiple Raspberry Pis ray carter <ray@zianet.com> - 2015-09-07 00:36 +0000
    Re: Something like a KVM switch for multiple Raspberry Pis davehigton14@gmail.com - 2015-09-07 03:54 -0700
    Re: Something like a KVM switch for multiple Raspberry Pis Gordon Levi <gordon@address.invalid> - 2015-09-08 00:54 +1000
    Re: Something like a KVM switch for multiple Raspberry Pis Andrew Smallshaw <andrews@sdf.lonestar.org> - 2015-09-13 12:45 +0000
      Re: Something like a KVM switch for multiple Raspberry Pis Alan Adams <alan@adamshome.org.uk> - 2015-09-13 19:22 +0100
      Re: Something like a KVM switch for multiple Raspberry Pis Jonathan Lane <tidux@faeroes.freeshell.org> - 2015-09-27 15:28 +0000
    Re: Something like a KVM switch for multiple Raspberry Pis Martin Gregorie <martin@address-in-sig.invalid> - 2015-09-13 13:48 +0000
      Re: Something like a KVM switch for multiple Raspberry Pis David James <david@tcs01.demon.co.uk> - 2015-09-13 14:22 +0000
        Re: Something like a KVM switch for multiple Raspberry Pis Martin Gregorie <martin@address-in-sig.invalid> - 2015-09-13 17:42 +0000
          Re: Something like a KVM switch for multiple Raspberry Pis David James <david@tcs01.demon.co.uk> - 2015-09-16 00:01 +0000
    Re: Something like a KVM switch for multiple Raspberry Pis DisneyWizard the Fantasmic! <wiz@FANTASMIC!disneywizard.com> - 2015-09-17 08:38 -0700
      Re: Something like a KVM switch for multiple Raspberry Pis rickman <gnuarm@gmail.com> - 2015-09-18 08:40 -0400
        Re: Something like a KVM switch for multiple Raspberry Pis Rob Morley <nospam@ntlworld.com> - 2015-09-18 14:26 +0100
        Re: Something like a KVM switch for multiple Raspberry Pis Martin Gregorie <martin@address-in-sig.invalid> - 2015-09-18 18:42 +0000
          Re: Something like a KVM switch for multiple Raspberry Pis rickman <gnuarm@gmail.com> - 2015-09-18 15:09 -0400
            Re: Something like a KVM switch for multiple Raspberry Pis "James Harris" <james.harris.1@gmail.com> - 2015-09-18 20:17 +0100
              Re: Something like a KVM switch for multiple Raspberry Pis Rob <nomail@example.com> - 2015-09-18 21:35 +0000
                Re: Something like a KVM switch for multiple Raspberry Pis "James Harris" <james.harris.1@gmail.com> - 2015-09-18 23:19 +0100
                  Re: Something like a KVM switch for multiple Raspberry Pis Rob <nomail@example.com> - 2015-09-19 06:48 +0000
                    Re: Something like a KVM switch for multiple Raspberry Pis "James Harris" <james.harris.1@gmail.com> - 2015-09-19 11:15 +0100
                  Re: Something like a KVM switch for multiple Raspberry Pis mm0fmf <none@mailinator.com> - 2015-09-19 08:13 +0100
                    Re: Something like a KVM switch for multiple Raspberry Pis "James Harris" <james.harris.1@gmail.com> - 2015-09-19 11:19 +0100
              Re: Something like a KVM switch for multiple Raspberry Pis rickman <gnuarm@gmail.com> - 2015-09-19 11:31 -0400
              Re: Something like a KVM switch for multiple Raspberry Pis druck <news@druck.org.uk> - 2015-09-19 19:39 +0100
                Re: Something like a KVM switch for multiple Raspberry Pis colonel_hack@yahoo.com - 2015-09-20 22:06 -0700

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#9680

"Rob" <nomail@example.com> wrote in message 
news:slrnmvp0th.87d.nomail@xs9.xs4all.nl...
> James Harris <james.harris.1@gmail.com> wrote:
>> "rickman" <gnuarm@gmail.com> wrote in message
>> news:mthne9$pjl$1@dont-email.me...
>>> On 9/18/2015 2:42 PM, Martin Gregorie wrote:
>>
>> ...
>>
>>>> Put that way, it sounds very like an RPi with USB keyboard+mouse +
>>>> HDMI
>>>> monitor plus an Ethernet hub/switch connecting all the RPIs 
>>>> together.
>>>>
>>>> Use the one with keyboard etc to login to the other headless RPis.
>>>
>>> Exactly.  Unless there is some advantage to having a device on the 
>>> pi
>>> that actually plugs into the HDMI/USB connectors to emulate the
>>> physical devices.
>>
>> Sure. Remote desktop or VNC etc can only work on a running OS and, 
>> what
>> is more, a running OS which has suitable apps. For bare-metal
>> programming, OS development and to see what's happening in the boot
>> process you need access to the real inputs and outputs.
>
> Then throw out the Raspberries, get a decent Intel/AMD based server,
> install VMware ESXi and you can do all the "bare metal programming",
> OS development etc that you like and have access to consoles over the
> network.

I have tried QEMU as a Raspberry Pi emulator but, IIRC, its emulation 
was not close enough.

I just looked for VMWare ESXi and found, in common with other VMWare 
products that it is hard to understand. I am not sure what the 
difference is between Vsphere and ESXi, for example. I know that Vsphere 
is a hypervisor but the video describing it spoke of installing ESXi. 
Two names for the same thing?

ESXi seems to be a type 1 hypervisor. Doesn't that mean that it has to 
run on a Raspberry Pi in order to emulate a Raspberry Pi?

If I installed ESXi (or some other VMWare product) on an Intel/AMD 
machine how are you suggesting I get that to emulate a Raspberry Pi 
accurately?

James

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#9683

James Harris <james.harris.1@gmail.com> wrote:
>
> "Rob" <nomail@example.com> wrote in message 
> news:slrnmvp0th.87d.nomail@xs9.xs4all.nl...
>> James Harris <james.harris.1@gmail.com> wrote:
>>> "rickman" <gnuarm@gmail.com> wrote in message
>>> news:mthne9$pjl$1@dont-email.me...
>>>> On 9/18/2015 2:42 PM, Martin Gregorie wrote:
>>>
>>> ...
>>>
>>>>> Put that way, it sounds very like an RPi with USB keyboard+mouse +
>>>>> HDMI
>>>>> monitor plus an Ethernet hub/switch connecting all the RPIs 
>>>>> together.
>>>>>
>>>>> Use the one with keyboard etc to login to the other headless RPis.
>>>>
>>>> Exactly.  Unless there is some advantage to having a device on the 
>>>> pi
>>>> that actually plugs into the HDMI/USB connectors to emulate the
>>>> physical devices.
>>>
>>> Sure. Remote desktop or VNC etc can only work on a running OS and, 
>>> what
>>> is more, a running OS which has suitable apps. For bare-metal
>>> programming, OS development and to see what's happening in the boot
>>> process you need access to the real inputs and outputs.
>>
>> Then throw out the Raspberries, get a decent Intel/AMD based server,
>> install VMware ESXi and you can do all the "bare metal programming",
>> OS development etc that you like and have access to consoles over the
>> network.
>
> I have tried QEMU as a Raspberry Pi emulator but, IIRC, its emulation 
> was not close enough.
>
> I just looked for VMWare ESXi and found, in common with other VMWare 
> products that it is hard to understand. I am not sure what the 
> difference is between Vsphere and ESXi, for example. I know that Vsphere 
> is a hypervisor but the video describing it spoke of installing ESXi. 
> Two names for the same thing?
>
> ESXi seems to be a type 1 hypervisor. Doesn't that mean that it has to 
> run on a Raspberry Pi in order to emulate a Raspberry Pi?
>
> If I installed ESXi (or some other VMWare product) on an Intel/AMD 
> machine how are you suggesting I get that to emulate a Raspberry Pi 
> accurately?

Just forget about the Raspberry thing.
I presume when you want to teach about programming it does not matter
if the platform is Raspberry or PC.  What ESXi gives you is a large
number of virtual Intel (PC) machines on a single box, and the way
to monitor it all via the network.  You can see the console and input
keyboard/mouse input over the network.  And the virtual machines of
course also have network so you can do SSH or VNC just as well.

This suggestion was just meant as a solution to the original problem
of setting up some system where multiple users in a classroom should
be able to work on a computer with someone monitoring their activity,
not a solution to the problem that was described in the first post
where already the assumption was made that it would be done on RPi
and some hardware was required to switch their HDMI/USB connections
onto a monitoring station.

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#9685

"Rob" <nomail@example.com> wrote in message 
news:slrnmvq1a2.lmg.nomail@xs9.xs4all.nl...
> James Harris <james.harris.1@gmail.com> wrote:
>>
>> "Rob" <nomail@example.com> wrote in message
>> news:slrnmvp0th.87d.nomail@xs9.xs4all.nl...
>>> James Harris <james.harris.1@gmail.com> wrote:
>>>> "rickman" <gnuarm@gmail.com> wrote in message
>>>> news:mthne9$pjl$1@dont-email.me...
>>>>> On 9/18/2015 2:42 PM, Martin Gregorie wrote:
>>>>
>>>> ...
>>>>
>>>>>> Put that way, it sounds very like an RPi with USB keyboard+mouse 
>>>>>> +
>>>>>> HDMI
>>>>>> monitor plus an Ethernet hub/switch connecting all the RPIs
>>>>>> together.
>>>>>>
>>>>>> Use the one with keyboard etc to login to the other headless 
>>>>>> RPis.
>>>>>
>>>>> Exactly.  Unless there is some advantage to having a device on the
>>>>> pi
>>>>> that actually plugs into the HDMI/USB connectors to emulate the
>>>>> physical devices.
>>>>
>>>> Sure. Remote desktop or VNC etc can only work on a running OS and,
>>>> what
>>>> is more, a running OS which has suitable apps. For bare-metal
>>>> programming, OS development and to see what's happening in the boot
>>>> process you need access to the real inputs and outputs.
>>>
>>> Then throw out the Raspberries, get a decent Intel/AMD based server,
>>> install VMware ESXi and you can do all the "bare metal programming",
>>> OS development etc that you like and have access to consoles over 
>>> the
>>> network.
>>
>> I have tried QEMU as a Raspberry Pi emulator but, IIRC, its emulation
>> was not close enough.
>>
>> I just looked for VMWare ESXi and found, in common with other VMWare
>> products that it is hard to understand. I am not sure what the
>> difference is between Vsphere and ESXi, for example. I know that 
>> Vsphere
>> is a hypervisor but the video describing it spoke of installing ESXi.
>> Two names for the same thing?
>>
>> ESXi seems to be a type 1 hypervisor. Doesn't that mean that it has 
>> to
>> run on a Raspberry Pi in order to emulate a Raspberry Pi?
>>
>> If I installed ESXi (or some other VMWare product) on an Intel/AMD
>> machine how are you suggesting I get that to emulate a Raspberry Pi
>> accurately?
>
> Just forget about the Raspberry thing.

Why? The whole point of some of what I am looking at is to run on the 
specific Raspberry Pi hardware. I think you are mixing my requirements 
up with someone else's.

> I presume when you want to teach about programming

I don't want to teach about programming... Perhaps you are thinking of 
the post by "DisneyWizard"?

> it does not matter
> if the platform is Raspberry or PC.  What ESXi gives you is a large
> number of virtual Intel (PC) machines on a single box, and the way
> to monitor it all via the network.  You can see the console and input
> keyboard/mouse input over the network.  And the virtual machines of
> course also have network so you can do SSH or VNC just as well.

I don't know about "DisneyWizard" but I currently use Oracle VirtualBox 
and DosBox for such testing on a PC. ESXi sounds like another option, 
though.

> This suggestion was just meant as a solution to the original problem
> of setting up some system where multiple users in a classroom should
> be able to work on a computer with someone monitoring their activity,

OK but that's nothing to do with me.

> not a solution to the problem that was described in the first post
> where already the assumption was made that it would be done on RPi
> and some hardware was required to switch their HDMI/USB connections
> onto a monitoring station.

Different requirement.

James

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#9684

On 18/09/2015 23:19, James Harris wrote:
>

> If I installed ESXi (or some other VMWare product) on an Intel/AMD
> machine how are you suggesting I get that to emulate a Raspberry Pi
> accurately?
>

Yes. How do you think the software in ARM based phones gets designed and 
written? How do you think the software for ECUs gets written? How do you 
think car dashboard display software gets written?

All of this stuff starts on accurate simulations of not just the CPU but 
large amounts of the silicon is simulated (in software) either as cycle 
accurate models for accurate bus simulation, or a loosely timed models 
which approximate bus performance or untimed models which allow software 
to be developed and tested.

Software simulations can be produced 18-24months before silicon is 
available and gives designers a huge startup boost. As soon as silicon 
is produced, code can be moved from simulation to hardware for real 
world testing.

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#9686

"mm0fmf" <none@mailinator.com> wrote in message 
news:vW7Lx.488418$Dx3.325055@fx39.am4...
> On 18/09/2015 23:19, James Harris wrote:
>>
>
>> If I installed ESXi (or some other VMWare product) on an Intel/AMD
>> machine how are you suggesting I get that to emulate a Raspberry Pi
>> accurately?
>>
>
> Yes.

"Yes"? The question was "how?". The word "Yes" doesn't answer it!

> How do you think the software in ARM based phones gets designed and 
> written? How do you think the software for ECUs gets written? How do 
> you think car dashboard display software gets written?
>
> All of this stuff starts on accurate simulations of not just the CPU 
> but large amounts of the silicon is simulated (in software) either as 
> cycle accurate models for accurate bus simulation, or a loosely timed 
> models which approximate bus performance or untimed models which allow 
> software to be developed and tested.
>
> Software simulations can be produced 18-24months before silicon is 
> available and gives designers a huge startup boost. As soon as silicon 
> is produced, code can be moved from simulation to hardware for real 
> world testing.

Sure. I don't disagree but you are talking about something else. In the 
paragraph above I was asking Rob how he proposed to get a good Raspberry 
Pi emulation on a PC. That would be useful. It turns out he was really 
thinking about someone else's problem, though, and AFIACT doesn't know 
of a good Raspberry Pi emulation that will run on standard PC hardware. 
If you do, of course,.....

James

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#9687

On 9/18/2015 3:17 PM, James Harris wrote:
> "rickman" <gnuarm@gmail.com> wrote in message
> news:mthne9$pjl$1@dont-email.me...
>> On 9/18/2015 2:42 PM, Martin Gregorie wrote:
>
> ....
>
>>> Put that way, it sounds very like an RPi with USB keyboard+mouse + HDMI
>>> monitor plus an Ethernet hub/switch connecting all the RPIs together.
>>>
>>> Use the one with keyboard etc to login to the other headless RPis.
>>
>> Exactly.  Unless there is some advantage to having a device on the pi
>> that actually plugs into the HDMI/USB connectors to emulate the
>> physical devices.
>
> Sure. Remote desktop or VNC etc can only work on a running OS and, what
> is more, a running OS which has suitable apps. For bare-metal
> programming, OS development and to see what's happening in the boot
> process you need access to the real inputs and outputs.

I'm divorcing from the follow on conversation and addressing this part.

Here is a block diagram of what I am reading is needed.

rPi
------+
  USB  |----- Keyboard
  USB  |----- Mouse
  HDMI |----- Monitor
  Pwr  |---------------Wall wart
  Eth  |---+
------+   |
           |
           |   +-------+ keyboard +-----+
           |   |       |----------|     |
           +---| Eth   |  mouse   |     |
               | Thing |----------| rPi |
           +---| Eth   |   HDMI   |     |
           |   |       |----------|     |
           |   +-------+          +-----+
           |
           |   +-------+ keyboard +-----+
           |   |       |----------|     |
           +---| Eth   |  mouse   |     |
               | Thing |----------| rPi |
           +---| Eth   |   HDMI   |     |
           |   |       |----------|     |
           |   +-------+          +-----+
           |
           |   +-------+ keyboard +-----+
           |   |       |----------|     |
           +---| Eth   |  mouse   |     |
               | Thing |----------| rPi |
           +---| Eth   |   HDMI   |     |
           |   |       |----------|     |
           V   +-------+          +-----+

I think this is what we are describing.  A main rPi (or some other 
device such as a PC) with a real keyboard, mouse and display connects 
via Ethernet to a series of "things" which provide the emulated mouse, 
kayboard and HDMI signals to a collection of rPi (or even other 
devices).  The main computer requires special software to drive the 
"things" via the Ethernet and the "things" will be some special hardware 
which responds to the commands and emulate the three I/Os.

I didn't draw the power because that is not clear to me if it is 
intended for the "thing" to channel power to the rPi or if the rPi will 
power the thing.  Since the keyboard/mouse will be plugged into at least 
one USB port, the rPi would power the "thing".

I don't see a need for a special "thing" on the head computer which has 
the physical keyboard/mouse/monitor attached.  This unit is just a 
computer with special software.  The "things" will need a slave USB port 
and an HDMI port to emulate a monitor, so I think that will require some 
special hardware.  I am not familiar with the HDMI spec, so I don't know 
exactly what will be required for that.  But otherwise, this will be not 
too much different from an rPi needing enough of a CPU to handle two 
Ethernet ports and being able to shuttle the HDMI graphics around.

I drew the Ethernet as a daisy chain.  Perhaps that should use a 
conventional star configuration with a hub/switch instead.

Another I/O that might be useful is something to force a reset, possibly 
even a power switch.  I run into a need for that more often than I like.

Thoughts?

-- 

Rick

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#9693

On 18/09/2015 20:17, James Harris wrote:
> Sure. Remote desktop or VNC etc can only work on a running OS and, what
> is more, a running OS which has suitable apps. For bare-metal
> programming, OS development and to see what's happening in the boot
> process you need access to the real inputs and outputs.

It sounds like what you need is a serial console in order to see the Pi 
boot, and to control it via a shell. You could get UART to Ethernet 
converters to be able to access them remotely.

---druck

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#9706

On Sat, 19 Sep 2015, druck wrote:

> It sounds like what you need is a serial console in order to see the Pi boot, 
> and to control it via a shell. You could get UART to Ethernet converters to 
> be able to access them remotely.

How remote does it need to be? Why not an old serial mouse kvm* using only 
the serial switch part. Connect the ``master pi'' serial pins to the 
switch and the other pi's to the other side. If they're all pis you won't 
need voltage convertion. If the master's a PC you'll need something.

   Ron

*or almost any ``mechanical'' switch.

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