Does linux support for microprocessor without MMU?

Does linux support for microprocessor without MMU?

[kjlin]

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Howdy,

I got an embedded MIPS board recently.
It has the following features:
- CPU implements a five-stage pipeline with performance similar to the MIPS R3000 pipeline.
- MIPS32 compatible instruction set
- R4000 style privileged resource architecture.
- Without MMU.

I am estimating the possibility of porting linux on it.
Can Linux/MIPS 2.2 or 2.4 support for such a board which without MMU ?
Because i consider it is the most difficult part in the porting process.
Am i right?

KJ




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Does linux support for microprocessor without MMU?

[kjlin]

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Howdy,

I got an embedded MIPS board recently.
It has the following features:
- CPU implements a five-stage pipeline with performance similar to the MIPS R3000 pipeline.
- MIPS32 compatible instruction set
- R4000 style privileged resource architecture.
- Without MMU.

I am estimating the possibility of porting linux on it.
Can Linux/MIPS 2.2 or 2.4 support for such a board which without MMU ?
Because i consider it is the most difficult part in the porting process.
Am i right?

KJ




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Re: Does linux support for microprocessor without MMU?

[Crossfire]

kjlin was once rumoured to have said:
> Howdy,
> 
> I got an embedded MIPS board recently.
> It has the following features:
> - CPU implements a five-stage pipeline with performance similar to the MIPS R3000 pipeline.
> - MIPS32 compatible instruction set
> - R4000 style privileged resource architecture.
> - Without MMU.
> 
> I am estimating the possibility of porting linux on it.
> Can Linux/MIPS 2.2 or 2.4 support for such a board which without MMU ?
> Because i consider it is the most difficult part in the porting process.
> Am i right?

the Standard Linux kernels all require an MMU.  However, there is a
version of the kernel known as "ucLinux" (Microcontroller Linux) which
will run on CPUs without MMU.

I don't know if ucLinux has a MIPS target yet.

C.
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Re: Does linux support for microprocessor without MMU?

[Joe deBlaquiere]

Crossfire wrote:

> kjlin was once rumoured to have said:
> 
>> Howdy,
>> 
>> I got an embedded MIPS board recently.
>> It has the following features:
>> - CPU implements a five-stage pipeline with performance similar to the MIPS R3000 pipeline.
>> - MIPS32 compatible instruction set
>> - R4000 style privileged resource architecture.
>> - Without MMU.
>> 
>> I am estimating the possibility of porting linux on it.
>> Can Linux/MIPS 2.2 or 2.4 support for such a board which without MMU ?
>> Because i consider it is the most difficult part in the porting process.
>> Am i right?
> 
> 
> the Standard Linux kernels all require an MMU.  However, there is a
> version of the kernel known as "ucLinux" (Microcontroller Linux) which
> will run on CPUs without MMU.
> 
> I don't know if ucLinux has a MIPS target yet.
> 
> C.

There isn't (yet) support for MIPS on uClinux.

-- 
Joe

(aka joe@uclinux.org)

Re: Does linux support for microprocessor without MMU?

[Geert Uytterhoeven]

On Wed, 21 Feb 2001, Joe deBlaquiere wrote:
> Crossfire wrote:
> > kjlin was once rumoured to have said:
> >> I got an embedded MIPS board recently.
> >> It has the following features:
> >> - CPU implements a five-stage pipeline with performance similar to the MIPS R3000 pipeline.
> >> - MIPS32 compatible instruction set
> >> - R4000 style privileged resource architecture.
> >> - Without MMU.
> >> 
> >> I am estimating the possibility of porting linux on it.
> >> Can Linux/MIPS 2.2 or 2.4 support for such a board which without MMU ?
> >> Because i consider it is the most difficult part in the porting process.
> >> Am i right?
> > 
> > the Standard Linux kernels all require an MMU.  However, there is a
> > version of the kernel known as "ucLinux" (Microcontroller Linux) which
> > will run on CPUs without MMU.
> > 
> > I don't know if ucLinux has a MIPS target yet.
> 
> There isn't (yet) support for MIPS on uClinux.

But it can't be that hard to add support for it...

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven ------------- Sony Software Development Center Europe (SDCE)
Geert.Uytterhoeven@sonycom.com ------------------- Sint-Stevens-Woluwestraat 55
Voice +32-2-7248626 Fax +32-2-7262686 ---------------- B-1130 Brussels, Belgium

Re: Does linux support for microprocessor without MMU?

[Joe deBlaquiere]

Geert Uytterhoeven wrote:

> On Wed, 21 Feb 2001, Joe deBlaquiere wrote:
> 
>> 
>> There isn't (yet) support for MIPS on uClinux.
> 
> 
> But it can't be that hard to add support for it...
> 
Porting the kernel isn't much worse than any other architectural port. 
Of course that's only a part of the story, since you'll need to port the 
C library (uClibc/uC-glibc) and you will have to play around with the 
object file format to make it work with FLAT binaries... If you're 
serious about doing uClinux you can find a somewhat cryptic article on 
porting to uClinux at:

http://www.redhat.com/embedded/technologies/resources

-- 
Joe

Re: Does linux support for microprocessor without MMU?

[kjlin]

Is the uClibc/uC-glibc platform dependent??
Can we use the "normal linux  glibc" instead of uClibc/uC-glibc when running
uClinux??
As to object file format, is it real necessary to modify the elf2flt
program?
On the other hand, there is an isssue which confuses me.
That is, i had already got a cross-compiler for compiling the "normal linux"
kernel used.
Should i need to remake a cross-compiler to compile the uClinux kernel and
applications?

Thanks.


----- Original Message -----
From: "Joe deBlaquiere" <jadb@redhat.com>
To: "Geert Uytterhoeven" <Geert.Uytterhoeven@sonycom.com>
Cc: "Crossfire" <xfire@xware.cx>; "kjlin" <kj.lin@viditec-netmedia.com.tw>;
<linux-mips@oss.sgi.com>
Sent: Friday, February 23, 2001 1:42 PM
Subject: Re: Does linux support for microprocessor without MMU?


> Geert Uytterhoeven wrote:
>
> > On Wed, 21 Feb 2001, Joe deBlaquiere wrote:
> >
> >>
> >> There isn't (yet) support for MIPS on uClinux.
> >
> >
> > But it can't be that hard to add support for it...
> >
> Porting the kernel isn't much worse than any other architectural port.
> Of course that's only a part of the story, since you'll need to port the
> C library (uClibc/uC-glibc) and you will have to play around with the
> object file format to make it work with FLAT binaries... If you're
> serious about doing uClinux you can find a somewhat cryptic article on
> porting to uClinux at:
>
> http://www.redhat.com/embedded/technologies/resources
>
> --
> Joe

Re: Does linux support for microprocessor without MMU?

[kjlin]

Is the uClibc/uC-glibc platform dependent??
Can we use the "normal linux  glibc" instead of uClibc/uC-glibc when running
uClinux??
As to object file format, is it real necessary to modify the elf2flt
program?
On the other hand, there is an isssue which confuses me.
That is, i had already got a cross-compiler for compiling the "normal linux"
kernel used.
Should i need to remake a cross-compiler to compile the uClinux kernel and
applications?

Thanks.


----- Original Message -----
From: "Joe deBlaquiere" <jadb@redhat.com>
To: "Geert Uytterhoeven" <Geert.Uytterhoeven@sonycom.com>
Cc: "Crossfire" <xfire@xware.cx>; "kjlin" <kj.lin@viditec-netmedia.com.tw>;
<linux-mips@oss.sgi.com>
Sent: Friday, February 23, 2001 1:42 PM
Subject: Re: Does linux support for microprocessor without MMU?


> Geert Uytterhoeven wrote:
>
> > On Wed, 21 Feb 2001, Joe deBlaquiere wrote:
> >
> >>
> >> There isn't (yet) support for MIPS on uClinux.
> >
> >
> > But it can't be that hard to add support for it...
> >
> Porting the kernel isn't much worse than any other architectural port.
> Of course that's only a part of the story, since you'll need to port the
> C library (uClibc/uC-glibc) and you will have to play around with the
> object file format to make it work with FLAT binaries... If you're
> serious about doing uClinux you can find a somewhat cryptic article on
> porting to uClinux at:
>
> http://www.redhat.com/embedded/technologies/resources
>
> --
> Joe