A few questions in embedded linux

A few questions in embedded linux

[Khai Trinh]

Hi folks,

We are developing a PCI adapter card based out of the
PPC440GP using MVL version 2.1 (kernel 2.4.17).

I have several issues as listed below:

1. I'd like to reserve a 4M RAM space for DMA
purposes. What I did was adding
CONFIG_CMD_LINE="root=60M" since our board has 64MB of
RAM. How do I know the system really now configure to
be only 60MB? How then can I get a virtual addr to the
4MB DMA buffer? I did ioremap() given it the start of
the 60MB RAM physical addr, but I get a bus error with
the following message:

Jan 1 00:01:42 199 kernel: __ioremap(): phys addr
3c00000 is RAM lr c000a57c

2. We have a list of files (ie: hhlfiles) required to
build a RAM DISK that is non networked. What other
files involved that we need to build a RAM DISK that
has full network capability( ie: telnet, ftp, ping,
rlogin, mount, etc...)?

3. When the ethernet driver comes up it does a bootp
request to find its IP address.... How do we configure
it such that it picks it up from a file or flash?

Thanks,

--Khai


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Re: A few questions in embedded linux

[Kedar Madineni]

Khai Trinh wrote:
> Hi folks,
>
> We are developing a PCI adapter card based out of the
> PPC440GP using MVL version 2.1 (kernel 2.4.17).
>
> I have several issues as listed below:
>
> 1. I'd like to reserve a 4M RAM space for DMA
> purposes. What I did was adding
> CONFIG_CMD_LINE="root=60M" since our board has 64MB of

mem=60M should be the option. Read the help.

> RAM. How do I know the system really now configure to
> be only 60MB? How then can I get a virtual addr to the
> 4MB DMA buffer? I did ioremap() given it the start of
> the 60MB RAM physical addr, but I get a bus error with
> the following message:

check and use high_memory ........



>
> Jan 1 00:01:42 199 kernel: __ioremap(): phys addr
> 3c00000 is RAM lr c000a57c
>
> 2. We have a list of files (ie: hhlfiles) required to
> build a RAM DISK that is non networked. What other
> files involved that we need to build a RAM DISK that
> has full network capability( ie: telnet, ftp, ping,
> rlogin, mount, etc...)?
>
> 3. When the ethernet driver comes up it does a bootp
> request to find its IP address.... How do we configure
> it such that it picks it up from a file or flash?
>
> Thanks,
>
> --Khai
>
>


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Re: A few questions in embedded linux

[Dr. Craig Hollabaugh]

>2. We have a list of files (ie: hhlfiles) required to
>build a RAM DISK that is non networked. What other
>files involved that we need to build a RAM DISK that
>has full network capability( ie: telnet, ftp, ping,
>rlogin, mount, etc...)?

route and ifconfig

>3. When the ethernet driver comes up it does a bootp
>request to find its IP address.... How do we configure
>it such that it picks it up from a file or flash?

init script running ifconfig and route.

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Re: A few questions in embedded linux

[Wolfgang Denk]

Dear Khai,

in message <20030117181544.14483.qmail@web11505.mail.yahoo.com> you wrote:
>
> We are developing a PCI adapter card based out of the
> PPC440GP using MVL version 2.1 (kernel 2.4.17).
>
> I have several issues as listed below:

Why don't you ask MV then?

> 1. I'd like to reserve a 4M RAM space for DMA
> purposes. What I did was adding
> CONFIG_CMD_LINE="root=60M" since our board has 64MB of
> RAM. How do I know the system really now configure to
> be only 60MB? How then can I get a virtual addr to the

It prints the memory when it boots, something like

Memory: 14200k available (1256k kernel code, 564k data, 52k init, 0k highmem)

> 2. We have a list of files (ie: hhlfiles) required to
> build a RAM DISK that is non networked. What other
> files involved that we need to build a RAM DISK that
> has full network capability( ie: telnet, ftp, ping,
> rlogin, mount, etc...)?

See for example ftp://ftp.denx.de/pub/LinuxPPC/usr/src/SELF/

> 3. When the ethernet driver comes up it does a bootp
> request to find its IP address.... How do we configure
> it such that it picks it up from a file or flash?

Use U-Boot - then you can configure these parameters as  "environment
variables",  which  can  be saved to flash/NVRAM/EEPROM and passed to
the Linux kernel.

Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Cogito cogito ergo cogito sum - "I think that I  think,  therefore  I
think that I am."          - Ambrose Bierce, "The Devil's Dictionary"

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Re: A few questions in embedded linux

[Roland Dreier]

>>>>> "Khai" == Khai Trinh <kqtrinh@yahoo.com> writes:

    Khai> Regarding to my question 1 below. After I check and use high
    Khai> mem, and CMDLINE="mem=60M", recompile my kernel, static link
    Khai> my driver using the 4M reserved RAM space, I got this
    Khai> message

    Khai> kernel: __ioremap(): phys addr 3c00000 is RAM lr c000a57c

Look at arch/ppc/mm/pgtable.c, where that message is being printed.
The kernel thinks that the address 3c00000 (which is 60 MB) is below
high_memory, which is where it thinks the top of memory is.

The most likely explanation is that you are doing something wrong when
you pass "mem=60M" to the kernel.

Have your driver print out virt_to_phys(high_memory) and check that
the kernel really thinks it only has 60 MB of memory.

 - Roland

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