[ECOS] What is the different between "ROM" and "ROMRAM" in the Bootup type ??

[ECOS] What is the different between "ROM" and "ROMRAM" in the Bootup type ??

[Steven_cheng]

Hi All,

    What is the different between  "ROM" and "ROMRAM" in the Bootup type ??

Reference to the description of the configure tool :

    This option is used to control where the application program will run,
either from RAM or ROM (flash) memory. ROM based applications must be self
contained, while RAM applications will typically assume the existence of a
debug environment, such as GDB stubs.



But What is the different between "ROM" and "ROMRAM"  ??

Thanks in advence.

//Steven Cheng




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Re: [ECOS] What is the different between "ROM" and "ROMRAM" in the Bootup type ??

[Andrew Lunn]

On Fri, Jul 01, 2005 at 05:48:45PM +0800, Steven_cheng wrote:
> Hi All,
> 
>     What is the different between  "ROM" and "ROMRAM" in the Bootup type ??
> 
> Reference to the description of the configure tool :
> 
>     This option is used to control where the application program will run,
> either from RAM or ROM (flash) memory. ROM based applications must be self
> contained, while RAM applications will typically assume the existence of a
> debug environment, such as GDB stubs.
> 
> 
> 
> But What is the different between "ROM" and "ROMRAM"  ??

ROMRAM starts in ROM, but copies itself into RAM.

        Andrew

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Re: [ECOS] What is the different between "ROM" and "ROMRAM" in the Bootup type ??

[Steven_cheng]

Dear Andrew,

    Thank you for you reply, but I still confuse about the following
questions.

1) When the board  powers on, does the CPU need to know which type and
vendor
of ROM flash?? (ex. AMD 29LV040B)

2) How does the CPU know the memory address which the ROM locates ??
because the files (xxx_romram.ldi/xxx_romram.h) only define the
RAM address and size.

Thnak you very much.

// Steven


----- Original Message ----- 
From: "Andrew Lunn" <andrew@lunn.ch>
To: "Steven_cheng" <05071@alphanetworks.com>
Cc: <ecos-discuss@sources.redhat.com>
Sent: Friday, July 01, 2005 8:49 PM
Subject: Re: [ECOS] What is the different between "ROM" and "ROMRAM" in the
Bootup type ??


> On Fri, Jul 01, 2005 at 05:48:45PM +0800, Steven_cheng wrote:
> > Hi All,
> >
> >     What is the different between  "ROM" and "ROMRAM" in the Bootup type
??
> >
> > Reference to the description of the configure tool :
> >
> >     This option is used to control where the application program will
run,
> > either from RAM or ROM (flash) memory. ROM based applications must be
self
> > contained, while RAM applications will typically assume the existence of
a
> > debug environment, such as GDB stubs.
> >
> >
> >
> > But What is the different between "ROM" and "ROMRAM"  ??
>
> ROMRAM starts in ROM, but copies itself into RAM.
>
>         Andrew
>
> -- 
> Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
> and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
>


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Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss

Re: [ECOS] What is the different between "ROM" and "ROMRAM" in the Bootup type ??

[Andrew Lunn]

On Sun, Jul 03, 2005 at 09:41:27AM +0800, Steven_cheng wrote:
> Dear Andrew,
> 
>     Thank you for you reply, but I still confuse about the following
> questions.
> 
> 1) When the board  powers on, does the CPU need to know which type and
> vendor of ROM flash?? (ex. AMD 29LV040B)

No. It should be able to read from any type/vendor. You only need to
know more when you come to erase/write. But its not the CPU that does
what, its you application program.

 
> 2) How does the CPU know the memory address which the ROM locates ??

It is hardwired. Read the data sheet for your processor and look at
the schematics to see what chip select it is using.

        Andrew

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Re: [ECOS] What is the different between "ROM" and "ROMRAM" in the Bootup type ??

[Steven_cheng]

Dear Andrew,

    I see, I will try it.

    Thank you for your help very much.


Steven Cheng


----- Original Message ----- 
From: "Andrew Lunn" <andrew@lunn.ch>
To: "Steven_cheng" <05071@alphanetworks.com>
Cc: "Andrew Lunn" <andrew@lunn.ch>; <ecos-discuss@sources.redhat.com>
Sent: Monday, July 04, 2005 3:41 AM
Subject: Re: [ECOS] What is the different between "ROM" and "ROMRAM" in the
Bootup type ??


> On Sun, Jul 03, 2005 at 09:41:27AM +0800, Steven_cheng wrote:
> > Dear Andrew,
> >
> >     Thank you for you reply, but I still confuse about the following
> > questions.
> >
> > 1) When the board  powers on, does the CPU need to know which type and
> > vendor of ROM flash?? (ex. AMD 29LV040B)
>
> No. It should be able to read from any type/vendor. You only need to
> know more when you come to erase/write. But its not the CPU that does
> what, its you application program.
>
>
> > 2) How does the CPU know the memory address which the ROM locates ??
>
> It is hardwired. Read the data sheet for your processor and look at
> the schematics to see what chip select it is using.
>
>         Andrew


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and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss