Vladimir Vassilevsky skrev 2009-12-18 15:56:
>
>
> Grant Edwards wrote:
>> On 2009-12-18, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
>>
>>
>>> I don't understand the idea of embedded linix. What is it useful for?
>>
>>
>> It's useful when you need a Linux/Unix OS in an embedded
>> project.  For example: you want to run a reasonably
>> full-featured web server, 
>
> But who may need full featured embedded web server?
>
>> you need an ssh server, ssl support,
>> IPv4 and IPv6 support with NAT and firewall features, DHCP
>> server and client, NTP server and client, and stuff like that.
>
> On embedded linix without memory management?

Only idiots run Linux without MMU today.

You can get an ARM9 with MMU for less than what you used to pay for an 8051.

>
> Don't know about ssl/ssh, IPv6 is large, the other abovementioned 
> things are no big deal.
>
>>> What is so good about it?
>>
>>
>> It's free.
>
> Please, not again. It is not free.
It is free, in the respect that you have full access to the internals.
It is free to aqcuire, not to maintain.
>
>> It works. 
>
> Kinda. After you spend ~months to make it work.
>
>> There's a lot of software that runs on
>> it. 
>
> Yes, there are few useful utilities, some of these indeed work very well.
>
>> It's been ported to everyting under the sun.
>
> I still don't understand the fascination with it.

Douglas Adams explained it with "Share and Enjoy!"


> Vladimir Vassilevsky
> DSP and Mixed Signal Design Consultant
> http://www.abvolt.com


-- 
Best Regards
Ulf Samuelsson
These are my own personal opinions, which may
or may not be shared by my employer Atmel Nordic AB

Vladimir Vassilevsky skrev 2009-12-18 15:10:
>
>
> David Brown wrote:
>> Vladimir Vassilevsky wrote:
>>> Grant Edwards wrote:
>>>> On 2009-12-16, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
>>>>> tama wrote:
>>>>>
>>>>>
>>>>>
>>>>>> I want to learn linux/ embedded linux.
>>>>>
>>>>>
>>>>> Book:
>>>>>
>>>>> P. Raghavan, A. Lad, S. Neelakandan
>>>>> "Embedded Linux System Design and Development"
>>>>
>>>>
>>>>
>>>> The O'Reilly book is also good:
>>>>
>>>>   Yaghmour, Masters, Ben-Yossef, and Gerum
>>>>   "Building Embedded Linux Systems" 
>>>
>>>
>>> Actually, having read the first book, I was very dissapointed about 
>>> Linux and ended up rolling my own OS.
>>>
>>
>> The OS you describe is a totally different beast than Linux - your OS 
>> and Linux solve very different problems and are suitable for very 
>> different applications.  If what you needed was something like the OS 
>> you wrote (and presumably it was!), then of course Linux would be a 
>> disappointment.
>
> I don't understand the idea of embedded linix. What is it useful for?
> What is so good about it?
>
> VLV

How much code does your SSH implementation take?
How much code does your SAMBA server take?
Do you have a driver for a capacitive touch sensor?
How many users can log into your machine?
Do you support all Wacom tablets or only a few?

List goes on and on and on.

Both Linux and RTOS'es have their applicability

-- 

Best Regards
Ulf Samuelsson
These are my own personal opinions, which may
or may not be shared by my employer Atmel Nordic AB

tamamontu skrev 2009-12-17 14:09:
>> One of the easiest ways to get a complete Linux thing together is to
>> download
>> "Buildroot" from www.buildroot.org
>>
>> You need a Linux machine and git. (or download a tarball)
>>
>> make at91sam9263ek_defconfig
>> make
>>
>> Wait a few hours and then you have
>>
>> * Cross Compiler
>> * First level Bootloader (at91bootstrap)
>> * Second level bootloader (U-Boot)
>> * Linux Kernel
>> * Root file system
>> * Scripts for U-boot environment
>>
>> The Samsung chips are not supported.
>> By building for another ARM chip, you can use the root fs,
>> but you have to build the bootloader and kernel manually.
>>
>> Alternatively, you can switch to a chip which IS supported well by
>> Buildroot (Read AT91s)
>> Note that the vanilla Buildroot is lagging for AT91.
>> I have an experimental version based on the Buildroot 2009.08 release
>>      
> which
>    
>> uses the latest 2.6.32 kernel. It is located in the private git area of
>> the Buildroot project.
>> Less tested than the vanilla stuff, but if you want to try the latest...
>> This also allows building the newer SAM9G45&  G10, which the vanilla
>> version does not.
>>
>> There are limitations to Buildroot, and I have started to use
>> OpenEmbedded www.openembedded.org.
>> When I tried building a full system with X and Gnome on the top,
>> it took 42 hours on my 2 GHz Pentium M laptop.
>>
>> I built myself a 2.66GHz  Core i7 machine this spring, and on this
>>      
> machine
>    
>> (8 virtual cores) it takes about 2 hours to complete the same job.
>> It builds a cross compiler in about 10 minutes :-)
>>      
>
> Thanks for your replies and info on the books.
>
> Ulf Thanks for explaining the steps in volved in this kind of project.
>
> At my work place we have a board which uses Cirrus Logic EP9307 chip + 5.6"
> touch screen. I have been asked to work on this project.
>
> I want to develop a touch screen based application which will control some
> peripheral device over CAN bus.
>    

There is really very little support for the EP93 series in Buildroot.
You can do what you want with an AT91SAM9263, and then it is more or 
less automatic with Buildroot.


> http://www.ibm.com/developerworks/library/l-embdev.html
> This link has a good explanation also.
>
>
> If I am not wrong buildroot is a gui based con-fig file generation utility
>
> When you say to manually compile the kernel and bootloader. Can you please
> give pointer to understand how it is done.
>    

You can study the source code for the AT91SAM9263 build recipes in 
buildroot for starters.


> cheers
> tama
>
>
>
> 	
> 					
> ---------------------------------------		
> This message was sent using the comp.arch.embedded web interface on
> http://www.EmbeddedRelated.com
>    


-- 
Best Regards
Ulf Samuelsson
These are my own personal opinions, which may
or may not be shared by my employer Atmel Nordic AB

Vladimir Vassilevsky wrote:

> Grant Edwards wrote:

>> It's useful when you need a Linux/Unix OS in an embedded
>> project.  For example: you want to run a reasonably
>> full-featured web server,
> 
> But who may need full featured embedded web server?

Current client sells big, complicated appliances to run at the core of 
small, complicated enterprises.  Has promised tons of customization, 
configurability, remote support.  WWW is the easiest way to provide and 
control all this stuff.  Trying to write it from scratch would take the rest 
of our lives.

	Mel.

On 2009-12-18, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
> Grant Edwards wrote:
>> On 2009-12-18, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
>>
>>>I don't understand the idea of embedded linix. What is it useful for?
>> 
>> It's useful when you need a Linux/Unix OS in an embedded
>> project.  For example: you want to run a reasonably
>> full-featured web server, 
>
> But who may need full featured embedded web server?

It's turtles all they way down.

>> you need an ssh server, ssl support,
>> IPv4 and IPv6 support with NAT and firewall features, DHCP
>> server and client, NTP server and client, and stuff like that.
>
> On embedded linix without memory management?

Who said anything about "without memory management"?

> Don't know about ssl/ssh, IPv6 is large,

Indeed.

> the other abovementioned things are no big deal.

Not everbody is wants to spend man-years of their spare time
writing every bit of what they need from scratch (after
designing a CPU, writing a compiler for it, no doubt).

>>>What is so good about it?
>> 
>> It's free.
>
> Please, not again. It is not free.

Whatever.

>> It works. 
>
> Kinda. After you spend ~months to make it work.

Nonsense.  I've and had Linux running on several different
embedded platforms in a couple days.

>> There's a lot of software that runs on
>> it.  
>
> Yes, there are few useful utilities, some of these indeed work
> very well.
>
>> It's been ported to everyting under the sun.
>
> I still don't understand the fascination with it.

Nobody is "fascinated" with it.  It's a tool.

-- 
Grant Edwards                   grante             Yow! !  Now I understand
                                  at               advanced MICROBIOLOGY and
                               visi.com            th' new TAX REFORM laws!!

Vladimir Vassilevsky wrote:
> 
> 
> Grant Edwards wrote:
>> On 2009-12-18, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
>>
>>
>>> I don't understand the idea of embedded linix. What is it useful for?
>>
>>
>> It's useful when you need a Linux/Unix OS in an embedded
>> project.  For example: you want to run a reasonably
>> full-featured web server, 
> 
> But who may need full featured embedded web server?
> 
>> you need an ssh server, ssl support,
>> IPv4 and IPv6 support with NAT and firewall features, DHCP
>> server and client, NTP server and client, and stuff like that.
> 
> On embedded linix without memory management?

You are mixing your terms here - the version of Linux for processors 
without an MMU is called "ucLinux".  "Embedded Linux" simply means Linux 
on an embedded system - which may or may not be the ucLinux variant.

And yes, all these can work fine on ucLinux.  There are some limitations 
with ucLinux applications (no "fork", for example), but most stuff works 
fine assuming you have enough resources - ucLinux systems are typically 
smaller with less memory.

> 
> Don't know about ssl/ssh, IPv6 is large, the other abovementioned things 
> are no big deal.
> 

Things like NAT, firewalling, and DHCP server and client are not large 
applications, but they take a lot of time and effort to write yourself. 
  Typically, you would want to use existing implementations - you can 
either buy code, or you can download some from somewhere.  With Linux 
you can easily get the code, and it is the same code that runs on every 
other Linux system - lots of features, and lots of testing.

When you are talking about secure code, such as ssl and ssh, you really 
want to use code you can trust - again, there are no implementations 
that have had as much testing or scrutiny as openssl and openssh, and 
with embedded Linux you can run these straight off (not that this means 
you can trust your builds of such software without testing!).

>>> What is so good about it?
>>
>>
>> It's free.
> 
> Please, not again. It is not free.
> 

It is "free as in speech" - something that some people see as a good 
thing, others see as a bad thing, and yet others don't understand.

For cost, you obviously have to consider many things (development time, 
board costs, licenses, etc.) before deciding how much it actually costs 
compared to alternative solutions.

>> It works. 
> 
> Kinda. After you spend ~months to make it work.
> 

That's very much a "it depends" situation.  Some people can get things 
working quickly, others take a long time.  It depends on your experience 
and knowledge beforehand, your application, your choice of processor and 
board, your choice of tools and your choice of distribution.  The same 
can be said of pretty much any complex system.

Embedded Linux is complex - there is a lot available for it, and your 
learning curve will depend very much on how deep you want to go, and how 
far you stray from well-trodden paths (such as well-supported evaluation 
cards).

>> There's a lot of software that runs on
>> it.  
> 
> Yes, there are few useful utilities, some of these indeed work very well.
> 

It's true - there are one or two utilities for Linux.

>> It's been ported to everyting under the sun.
> 
> I still don't understand the fascination with it.
> 

It's not for everybody, and it's not for every application.  I don't use 
embedded Linux much - most of my systems are too small for it.  But it 
certainly has its useful features that you can't (practically) get any 
other way.

Vladimir Vassilevsky wrote:
> 
> 
> David Brown wrote:
>> Vladimir Vassilevsky wrote:
>>> Grant Edwards wrote:
>>>> On 2009-12-16, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
>>>>> tama wrote:
>>>>>
>>>>>
>>>>>
>>>>>> I want to learn linux/ embedded linux.
>>>>>
>>>>>
>>>>> Book:
>>>>>
>>>>> P. Raghavan, A. Lad, S. Neelakandan
>>>>> "Embedded Linux System Design and Development"
>>>>
>>>>
>>>>
>>>> The O'Reilly book is also good:
>>>>
>>>>   Yaghmour, Masters, Ben-Yossef, and Gerum
>>>>   "Building Embedded Linux Systems" 
>>>
>>>
>>> Actually, having read the first book, I was very dissapointed about 
>>> Linux and ended up rolling my own OS.
>>>
>>
>> The OS you describe is a totally different beast than Linux - your OS 
>> and Linux solve very different problems and are suitable for very 
>> different applications.  If what you needed was something like the OS 
>> you wrote (and presumably it was!), then of course Linux would be a 
>> disappointment.
> 
> I don't understand the idea of embedded linix. What is it useful for?
> What is so good about it?
> 

It is useful if you need a large and flexible operating system that can 
run existing software and support a wide range of peripherals.  It is 
also good if you want powerful networking support, or if you want to be 
able to run a variety of different programs.

It is of course important to realise what embedded Linux really is - it 
is a full power *nix-style operating system, typically with fewer 
drivers enabled by default and typically packaged up with smaller 
utilities than standard Linux.  It is much bigger than the type of OS 
you have written, and though it can provide close to real time 
performance, it is not real-time as such (in some cases, "close to real 
time" is good enough - in other cases, it's a disaster waiting to happen).

For example, I use openwrt embedded linux on wireless routers.  This 
gives me a great deal of flexibility on the network setup - I can use a 
full-featured firewall, wireless networking, vpn setups, virtual LANs, 
dhcp server, dns server, etc., etc.  On devices (not ones I have used) 
which have enough flash and ram, you can use it as a print server or a 
file server (using a usb disk).  Although some manufacturers use Linux 
in their firmware, many use something like VxWorks - such an RTOS has a 
fraction of the features of embedded Linux, and is no faster or more 
reliable (in this sort of application).

As another example, I was working for a while with an AVR32 processor 
running Linux on an STK1000 starter kit.  I could do pretty much 
everything over the network - only the bootloader was actually in the 
flash on the board.  It collected the Linux kernel from my virtual PC, 
and the root file system was mounted over nfs (again from the virtual 
PC).  Some files were on the virtual PC, others on my "real" PC running 
windows - the Linux kernel on the board could access them just like any 
other networked Linux machine.  I could edit software on the host PC, 
compile it on the virtual PC, and run it (via telnet) on the embedded 
PC.  When I needed more RAM than the starter kit board had, I made a 
swap "drive" as a file on the virtual PC and mounted it as swap on the 
embedded system - obviously it was a bit slower than real RAM, but it 
was much easier than trying to solder new ram chips onto the board!

Embedded Linux is certainly not the answer to all embedded systems, but 
it certainly /can/ be useful on larger embedded systems.

Grant Edwards wrote:
> On 2009-12-18, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
> 
> 
>>I don't understand the idea of embedded linix. What is it useful for?
> 
> 
> It's useful when you need a Linux/Unix OS in an embedded
> project.  For example: you want to run a reasonably
> full-featured web server, 

But who may need full featured embedded web server?

> you need an ssh server, ssl support,
> IPv4 and IPv6 support with NAT and firewall features, DHCP
> server and client, NTP server and client, and stuff like that.

On embedded linix without memory management?

Don't know about ssl/ssh, IPv6 is large, the other abovementioned things 
are no big deal.

>>What is so good about it?
> 
> 
> It's free.

Please, not again. It is not free.

> It works. 

Kinda. After you spend ~months to make it work.

> There's a lot of software that runs on
> it.  

Yes, there are few useful utilities, some of these indeed work very well.

> It's been ported to everyting under the sun.

I still don't understand the fascination with it.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

Grant Edwards <invalid@invalid.invalid> writes:

> On 2009-12-18, Vladimir Vassilevsky <nospam@nowhere.com> wrote:
>
>> I don't understand the idea of embedded linix. What is it useful for?
>
> It's useful when you need a Linux/Unix OS in an embedded
> project.  For example: you want to run a reasonably
> full-featured web server, you need an ssh server, ssl support,
> IPv4 and IPv6 support with NAT and firewall features, DHCP
> server and client, NTP server and client, and stuff like that.
>
>> What is so good about it?
>
> It's free.  It works.  There's a lot of software that runs on
> it.  It's been ported to everyting under the sun.

Including the Sun actually :-)

 S.