booting uclinux from u-boot

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originally posted by ankur@May 29 2006, 04:24 AM

hi all

i am trying to boot uclinux from u-boot on 2s60 board.

i have one doubt regarding exception vector table entry point address.

what i have observed in uclinux (head.s) that exception vector table entry point jump instruction sits at base addr of ram + 0x20 offset, same information i have given in hardware configuration file in sopc builder (.sof).

and same location is used for u-boot's execption vector table (specified in the u-boot config file).

my sdram start address is 0x0100_0000.

so exception vector table sits at 0x0100_0020 in both the cases of u-boot and uclinux.

the kernel image has entry_address at 0x0100_0000.

now if i download kernel image through u-boot, then exception table gets overwritten by kernel image and u-boot hangs.

please share your experience with how you deal with this issue. i mean when you boot kernel from u-boot then which address is given for exception vector table. or it's ok to use same addr there is some other issue ?

thanks

ankur

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=15652)

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hi all,

I can download my kernel image file in the sdram. There were some misunderstanding with CFG_NIOS_CPU_VEC_BASE and CFG_EXCEPTION_ADDR.

Now both I made equal to 0x0100_0020.

But still I can&#39;t boot my kernel.

I am downloading uncompressed kernel through tftpboot at 0x0100_0000.

Then I give bootm 0x0100_0000

Is it fine or should I change the location ??

thanks

Ankur

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originally posted by ankur+may 29 2006, 08:18 am--><div class='quotetop'>quote (ankur @ may 29 2006, 08:18 am)</div>

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<!--quotebegin-ankur@May 29 2006, 04:24 AM

hi all

i am trying to boot uclinux from u-boot on 2s60 board.

i have one doubt regarding exception vector table entry point address.

what i have observed in uclinux (head.s) that exception vector table entry point jump instruction sits at base addr of ram + 0x20 offset, same information i have given in hardware configuration file in sopc builder (.sof).

and same location is used for u-boot&#39;s execption vector table (specified in the u-boot config file).

my sdram start address is 0x0100_0000.

so exception vector table sits at 0x0100_0020 in both the cases of u-boot and uclinux.

the kernel image has entry_address at 0x0100_0000.

now if i download kernel image through u-boot, then exception table gets overwritten by kernel image and u-boot hangs.

please share your experience with how you deal with this issue. i mean when you boot kernel from u-boot then which address is given for exception vector table. or it&#39;s ok to use same addr there is some other issue ?

thanks

ankur

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=15652)

--- quote end ---

--- Quote End ---

hi all,

I can download my kernel image file in the sdram. There were some misunderstanding with CFG_NIOS_CPU_VEC_BASE and CFG_EXCEPTION_ADDR.

Now both I made equal to 0x0100_0020.

But still I can&#39;t boot my kernel.

I am downloading uncompressed kernel through tftpboot at 0x0100_0000.

Then I give bootm 0x0100_0000

Is it fine or should I change the location ??

thanks

Ankur

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=15664)</div>

[/b]

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Hi Ankur,

> There were some misunderstanding with CFG_NIOS_CPU_VEC_BASE and

> CFG_EXCEPTION_ADDR.

> Now both I made equal to 0x0100_0020.

First, don&#39;t use CFG_NIOS_CPU_VEC_BASE ... this is an old (and totally brain-damaged) obfuscation

that was foolishly added to some Nios-32 u-boot board configurations -- it is not used in the

Nios II sources. And please don&#39;t ask for any details about CFG_NIOS_CPU_VEC_BASE

-- I&#39;ll just end up embarrassing myself with an endless rant ;-)

Second, please use the code from: http://www.psyent.com/download (http://www.psyent.com/download) -- it contains all of the patches

that have been submitted to the u-boot project (and are still pending). If you&#39;re using code directly

from the u-boot project you will likely have problems without the patches.

> am downloading uncompressed kernel through tftpboot at 0x0100_0000.

> Then I give bootm 0x0100_0000

> Is it fine or should I change the location ??

Change this -- you are overwriting your exception trampoline during download. The first

interrupt will put the CPU in the weeds. Load the image somewhere higher in memory.

The &#39;bootm&#39; command will copy (and optionally decompress) the image to the load

address you specified with mkimage, after disabling interrupts. Try downloading to

0140_0000 for example (but leave the load address and entry point at 0100_0000). Then,

==> bootm 1400000

Regards,

--Scott

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originally posted by smcnutt@May 30 2006, 07:39 PM

hi ankur,

> there were some misunderstanding with cfg_nios_cpu_vec_base and

> cfg_exception_addr.

> now both i made equal to 0x0100_0020.

first, don&#39;t use cfg_nios_cpu_vec_base ... this is an old (and totally brain-damaged) obfuscation

that was foolishly added to some nios-32 u-boot board configurations -- it is not used in the

nios ii sources. and please don&#39;t ask for any details about cfg_nios_cpu_vec_base

-- i&#39;ll just end up embarrassing myself with an endless rant ;-)

second, please use the code from: http://www.psyent.com/download (http://www.psyent.com/download) -- it contains all of the patches

that have been submitted to the u-boot project (and are still pending). if you&#39;re using code directly

from the u-boot project you will likely have problems without the patches.

> am downloading uncompressed kernel through tftpboot at 0x0100_0000.

> then i give bootm 0x0100_0000

> is it fine or should i change the location ??

change this -- you are overwriting your exception trampoline during download. the first

interrupt will put the cpu in the weeds. load the image somewhere higher in memory.

the &#39;bootm&#39; command will copy (and optionally decompress) the image to the load

address you specified with mkimage, after disabling interrupts.[/b] Try downloading to

0140_0000 for example (but leave the load address and entry point at 0100_0000). Then,

==> bootm 1400000

Regards,

--Scott

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=15700)

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[/b]

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hi Scott,

thanks, for the reply. Actually I was using u-boot -1.1.2 taken from source forge. (I know its old now). But after following your instructions uclinux is booting now.

thanks once again

Ankur