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Re: Booting rootfs over TFTP with RedBoot
- From: Gary Thomas <gary at mlbassoc dot com>
- To: Stephen Crocker <scrocker at ampltd dot com>
- Cc: ecos-discuss at ecos dot sourceware dot org
- Date: Fri, 14 May 2010 05:52:03 -0600
- Subject: Re: [ECOS] Booting rootfs over TFTP with RedBoot
- References: <4BED360E.70906@ampltd.com>
On 05/14/2010 05:37 AM, Stephen Crocker wrote:
I am currently attempting to test a system using OpenWRT on a Gateworks
Cambria board with an XScale CPU. I have produced a new rootfs for
experimentation purposes but I do not want to overwrite the rootfs that
is currently in the flash.
I have successfully used the following commands in the past to load
kernels remotely with an existing rootfs:
load -r -b 0x00800000 -h 192.168.1.241 -m tftp zImage
exec
However, I am unable to see how I can do the same for a rootfs loaded
over TFTP. The flash has the following layout:
RedBoot> fis list
Name FLASH addr Mem addr Length Entry point
RedBoot 0x50000000 0x50000000 0x00080000 0x00000000
linux 0x50080000 0x00800000 0x00100000 0x00800000
rootfs 0x50180000 0x00800000 0x01E60000 0x00800000
FIS directory 0x51FE0000 0x51FE0000 0x0001F000 0x00000000
RedBoot config 0x51FFF000 0x51FFF000 0x00001000 0x00000000
RedBoot>
Clearly the kernel and rootfs are intended to be loaded into RAM at the
same location, but this is not possible if the rootfs is to be loaded
over TFTP. Is there any way to specify a different rootfs offset to the
kernel?
The rootfs currently in flash is very important for testing something
else, so I do not want to risk losing it.
The file system (rootfs) used by Linux is *not* loaded into RAM,
rather used directly from the FLASH.
Given the size of the file system, it would seem that your only
choice would be to overwrite the FLASH with your test image.
Do you have any way of copying/preserving the FLASH before trying
such an operation?
Another possibility would be to run your test file system via NFS.
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Gary Thomas | Consulting for the
MLB Associates | Embedded world
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