Where is the first entry point for linux-mips boot?

Where is the first entry point for linux-mips boot?

[machael thailer]

Hello,all:

    Now I plan to port linux on our mips-based board. Since it is the first
time for me to work on linux-mips, I have several questions to ask:

    There are many many subdirectories in arch/mips, I don't know where is
the FIRST entry point for embedded linux-mips boot process? I find that
there is "kernel_entry" in arch/mips/kernel/head.S. I know this is the entry
point for linux kernel ,but it is not the FIRST entry point for embedded
linux-mips boot process. So my questions is :
    After the board initializations finish, it should load linux kernel into
RAM and jump there .  Just before it runs the linux kernel, who calls
"kernel_entry"?
    I don't know whether I have expressed my meaning apparently. Hope you
can understand me.

Thank you very much.

machael thailer

Where is the first entry point for linux-mips boot?

[machael thailer]

Hello,all:

    Now I plan to port linux on our mips-based board. Since it is the first
time for me to work on linux-mips, I have several questions to ask:

    There are many many subdirectories in arch/mips, I don't know where is
the FIRST entry point for embedded linux-mips boot process? I find that
there is "kernel_entry" in arch/mips/kernel/head.S. I know this is the entry
point for linux kernel ,but it is not the FIRST entry point for embedded
linux-mips boot process. So my questions is :
    After the board initializations finish, it should load linux kernel into
RAM and jump there .  Just before it runs the linux kernel, who calls
"kernel_entry"?
    I don't know whether I have expressed my meaning apparently. Hope you
can understand me.

Thank you very much.

machael thailer

Re: Where is the first entry point for linux-mips boot?

[Ralf Baechle]

On Sat, Aug 04, 2001 at 10:16:27AM +0800, machael thailer wrote:

>     There are many many subdirectories in arch/mips, I don't know where is
> the FIRST entry point for embedded linux-mips boot process? I find that
> there is "kernel_entry" in arch/mips/kernel/head.S. I know this is the entry
> point for linux kernel ,but it is not the FIRST entry point for embedded
> linux-mips boot process. So my questions is :
>     After the board initializations finish, it should load linux kernel into
> RAM and jump there .  Just before it runs the linux kernel, who calls
> "kernel_entry"?

The firmware or bootloader.

  Ralf

Re: Where is the first entry point for linux-mips boot?

[Marc Karasek]

The firmware or bootloader.  For some examples of this look at redboot
from RedHat or yamon (yet another monitor) from MIPS (I think).  

Keep in mind these will prob require a seperate cross-compiler.  I have
yet to test compiling a boot monitor with linux gcc cross compiler.  You
can get one from either MIPS or Algorythmics (www.algor.co.uk).  I have
used both of these to build both of the above monitors.  

Any other questions, email me..

/*************************
Marc Karasek
Sr. Firmware Engineer
iVivity Inc.
marc_karasek@ivivity.com
(770) 986-8925
(770) 986-8926 Fax
*************************/  

On 04 Aug 2001 10:16:27 +0800, machael thailer wrote:
> Hello,all:
> 
>     Now I plan to port linux on our mips-based board. Since it is the first
> time for me to work on linux-mips, I have several questions to ask:
> 
>     There are many many subdirectories in arch/mips, I don't know where is
> the FIRST entry point for embedded linux-mips boot process? I find that
> there is "kernel_entry" in arch/mips/kernel/head.S. I know this is the entry
> point for linux kernel ,but it is not the FIRST entry point for embedded
> linux-mips boot process. So my questions is :
>     After the board initializations finish, it should load linux kernel into
> RAM and jump there .  Just before it runs the linux kernel, who calls
> "kernel_entry"?
>     I don't know whether I have expressed my meaning apparently. Hope you
> can understand me.
> 
> Thank you very much.
> 
> machael thailer
> 
> 
-- 
/*************************
Marc Karasek
Sr. Firmware Engineer
iVivity Inc.
marc_karasek@ivivity.com
(770) 986-8925
(770) 986-8926 Fax
*************************/

Re: Where is the first entry point for linux-mips boot?

[machael thailer]

----- Original Message -----
From: "Ralf Baechle" <ralf@oss.sgi.com>
To: "machael thailer" <dony.he@huawei.com>
Cc: <linux-mips@oss.sgi.com>
Sent: Saturday, August 04, 2001 1:10 PM
Subject: Re: Where is the first entry point for linux-mips boot?


> On Sat, Aug 04, 2001 at 10:16:27AM +0800, machael thailer wrote:
>
> >     There are many many subdirectories in arch/mips, I don't know where
is
> > the FIRST entry point for embedded linux-mips boot process? I find that
> > there is "kernel_entry" in arch/mips/kernel/head.S. I know this is the
entry
> > point for linux kernel ,but it is not the FIRST entry point for embedded
> > linux-mips boot process. So my questions is :
> >     After the board initializations finish, it should load linux kernel
into
> > RAM and jump there .  Just before it runs the linux kernel, who calls
> > "kernel_entry"?
>
> The firmware or bootloader.

Another question:

After my custom board  finished initializations, It should load "linux
kernel" into RAM.
The question is :  Is this a compressed "linux kernel" just like vmlinux.gz
of X86 that I should load? Or is it "/usr/src/linux/vmlinux" that is not
compressed that I should load? And what RAM address should it loaded at?
Since it is linked at 0x80200000,Should I load there or at somewhere else?

Thanks very much.

machael

Re: Where is the first entry point for linux-mips boot?

[machael thailer]

----- Original Message -----
From: "Ralf Baechle" <ralf@oss.sgi.com>
To: "machael thailer" <dony.he@huawei.com>
Cc: <linux-mips@oss.sgi.com>
Sent: Saturday, August 04, 2001 1:10 PM
Subject: Re: Where is the first entry point for linux-mips boot?


> On Sat, Aug 04, 2001 at 10:16:27AM +0800, machael thailer wrote:
>
> >     There are many many subdirectories in arch/mips, I don't know where
is
> > the FIRST entry point for embedded linux-mips boot process? I find that
> > there is "kernel_entry" in arch/mips/kernel/head.S. I know this is the
entry
> > point for linux kernel ,but it is not the FIRST entry point for embedded
> > linux-mips boot process. So my questions is :
> >     After the board initializations finish, it should load linux kernel
into
> > RAM and jump there .  Just before it runs the linux kernel, who calls
> > "kernel_entry"?
>
> The firmware or bootloader.

Another question:

After my custom board  finished initializations, It should load "linux
kernel" into RAM.
The question is :  Is this a compressed "linux kernel" just like vmlinux.gz
of X86 that I should load? Or is it "/usr/src/linux/vmlinux" that is not
compressed that I should load? And what RAM address should it loaded at?
Since it is linked at 0x80200000,Should I load there or at somewhere else?

Thanks very much.

machael

Re: Where is the first entry point for linux-mips boot?

[Ralf Baechle]

On Fri, Aug 17, 2001 at 11:11:21AM +0800, machael thailer wrote:

> After my custom board  finished initializations, It should load "linux
> kernel" into RAM.
> The question is :  Is this a compressed "linux kernel" just like vmlinux.gz
> of X86 that I should load? Or is it "/usr/src/linux/vmlinux" that is not
> compressed that I should load?

The standard MIPS kernel doesn't support compressed kernels on MIPS.

> And what RAM address should it loaded at?  Since it is linked at
> 0x80200000,Should I load there or at somewhere else?

Obviously to the address it's linked for.  You can adjust that address
as you need.  With compressed kernels it may be necessary to choose a
different address however so the decompressed kernel doesn't overwrite
the compressed kernel during compression.

  Ralf

Re: Where is the first entry point for linux-mips boot?

[machael thailer]

----- Original Message -----
From: "Ralf Baechle" <ralf@oss.sgi.com>
To: "machael thailer" <dony.he@huawei.com>
Cc: <linux-mips@oss.sgi.com>
Sent: Friday, August 17, 2001 11:26 AM
Subject: Re: Where is the first entry point for linux-mips boot?


> On Fri, Aug 17, 2001 at 11:11:21AM +0800, machael thailer wrote:
>
> > After my custom board  finished initializations, It should load "linux
> > kernel" into RAM.
> > The question is :  Is this a compressed "linux kernel" just like
vmlinux.gz
> > of X86 that I should load? Or is it "/usr/src/linux/vmlinux" that is not
> > compressed that I should load?
>
> The standard MIPS kernel doesn't support compressed kernels on MIPS.
>
> > And what RAM address should it loaded at?  Since it is linked at
> > 0x80200000,Should I load there or at somewhere else?
>
> Obviously to the address it's linked for.  You can adjust that address
> as you need.  With compressed kernels it may be necessary to choose a
> different address however so the decompressed kernel doesn't overwrite
> the compressed kernel during compression.

If I load the kernel to RAM address 0x80200000, is this a virtual address or
physical address at this time? Since my RAM can not be so large, I guess
this is virtual address,right? Should I enable MMU in my board
initializations?


Thank you once again.

machael

Re: Where is the first entry point for linux-mips boot?

[machael thailer]

----- Original Message -----
From: "Ralf Baechle" <ralf@oss.sgi.com>
To: "machael thailer" <dony.he@huawei.com>
Cc: <linux-mips@oss.sgi.com>
Sent: Friday, August 17, 2001 11:26 AM
Subject: Re: Where is the first entry point for linux-mips boot?


> On Fri, Aug 17, 2001 at 11:11:21AM +0800, machael thailer wrote:
>
> > After my custom board  finished initializations, It should load "linux
> > kernel" into RAM.
> > The question is :  Is this a compressed "linux kernel" just like
vmlinux.gz
> > of X86 that I should load? Or is it "/usr/src/linux/vmlinux" that is not
> > compressed that I should load?
>
> The standard MIPS kernel doesn't support compressed kernels on MIPS.
>
> > And what RAM address should it loaded at?  Since it is linked at
> > 0x80200000,Should I load there or at somewhere else?
>
> Obviously to the address it's linked for.  You can adjust that address
> as you need.  With compressed kernels it may be necessary to choose a
> different address however so the decompressed kernel doesn't overwrite
> the compressed kernel during compression.

If I load the kernel to RAM address 0x80200000, is this a virtual address or
physical address at this time? Since my RAM can not be so large, I guess
this is virtual address,right? Should I enable MMU in my board
initializations?


Thank you once again.

machael

Re: Where is the first entry point for linux-mips boot?

[Ralf Baechle]

On Fri, Aug 17, 2001 at 06:09:48PM +0800, machael thailer wrote:

> If I load the kernel to RAM address 0x80200000, is this a virtual address or
> physical address at this time? Since my RAM can not be so large, I guess
> this is virtual address,right? Should I enable MMU in my board
> initializations?

A virtual address in KSEG0.  A MIPS MMU has no enable bit, it's always
active.

  Ralf