Re: kernel memory mapping problem

In message [off-list ref] you wrote:

But my functions are serial running on PPC82xx, its
means that when I mapped the the address using __pa(
(void *)tmp) to bd_address, then reading the BD's
status and control registers, if OK, then return from

Just a stupid question: what are the alignment requirements of a  BD,
and which alignment is guaranteed for your tmp buffer?


Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
This cultural mystique surrounding the  biological  function  --  you
realize humans are overly preoccupied with the subject.
	-- Kelinda the Kelvan, "By Any Other Name", stardate 4658.9

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Dear all,

This question may be simple for you, but it doesn't let me sleeping.

I have linux2.4.1 from Lineo runing on ppc8250, IMMR = 0xF0000000, in my driver function, I can directly access 0xF00xxxxx( internal memory area on PPC's chip), why? I think , in device driver, we also use logical memory, when accessing physical address, it should first map this address to be accessed by hardware. Is it right?

Another, I write a character driver to operate I2C device. When passing a logical address pointer to BD's address pointer that allocated by function kmalloc().  I can't correctly operate I2C device, But when I used free memory located in IMM ( 0xF00037C0 ~ 0xF00037F0  ) and directly pass this address to BD's buffer pointer, I can correctly operate I2C device. I also try to use function __pa() and virt_to_phys()  to map logical address to physical address, The driver still can't work OK.

Any comments and suggestions are appreciated!

John Zhou

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 Does Linux kernel use paging or BAT registers before executing "/bin/sh"?
How can I test if paging works fine?

  My Linux kernel crashes while it accesses page table entry for argument
page which is called
   load_elf_binary --> setup_arg_pages --> put_dirty_page.
The address of page table entry is 0xb0beffc which is not a valid address.
When the kernel accesses that address, it crashes.
I suspect that paging may not work properly.

Did anybody have this problem?

 Dong-In


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Hi all,

I want to get some detail documents about how to use busybox to make a ramdisk!!  Does anybody know? Is it to use mkinitrd ?

Thanks & Regards
John Zhou

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Brian Padalino wrote:

... there is also a good tutorial on how to create ramdisk images.

http://www.linux.org/docs/ldp/howto/Bootdisk-HOWTO/buildroot.html

The only thing that I do differently is that I use a loopback device like
so:
  mount -t ext2 filename /mnt/image -o loop
This stops mount from complaining to me and I like that.

I highly recommend using genext2fs instead of a loopback mount;
that way you don't need to be root at all when making the image.

Stock genext2fs doesn't handle ramdisks bigger than 8MB, but
there are patches that fix this, and I've been using them happily
for about nine months.  (Maybe they're in the mainline now; not sure.)
- Dan

--
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045


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John,

I kind of cheated and used the DENX ELDK (http://www.denx.de) ramdisk that
came with his stuff (mainly for the /dev entries).

But there is also a good tutorial on how to create ramdisk images.

http://www.linux.org/docs/ldp/howto/Bootdisk-HOWTO/buildroot.html

The only thing that I do differently is that I use a loopback device like
so:
  mount -t ext2 filename /mnt/image -o loop
This stops mount from complaining to me and I like that.

Hope this helps and good luck!

Cheers,
Brian Padalino


-----Original Message-----
From: owner-linuxppc-embedded@lists.linuxppc.org
[mailto:owner-linuxppc-embedded@lists.linuxppc.org]On Behalf Of John
Zhou
Sent: Thursday, August 28, 2003 5:54 AM
To: linuxppc-embedded@lists.linuxppc.org
Subject: how to use busybox to make a ramdisk?



Hi all,

I want to get some detail documents about how to use busybox to make a
ramdisk!!  Does anybody know? Is it to use mkinitrd ?

Thanks & Regards
John Zhou


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/