[IAEP] [Testing] Dextrose Install Snags
cbigenho at hotmail.com
Sun Sep 12 23:09:17 EDT 2010
Date: Sun, 12 Sep 2010 16:41:34 -1000
From: wmb at laptop.org
To: cbigenho at hotmail.com
CC: testing at lists.laptop.org; iaep at lists.sugarlabs.org; support-gang at laptop.org
Subject: Re: [Testing] Dextrose Install Snags
On 9/12/2010 4:12 PM, Caryl Bigenho wrote:
I was trying to
install Dextrose on an XO-1.5 today. I was following the
instructions on: http://wiki.sugarlabs.org/go/Dextrose
There was only one
file listed to download for the XO-1.5 : os373pyg.zd. I
followed the directions on the page and got an error message
that the file was all in "one chunk"
at which step in the directions did the error message appear?
The message appears after entering " fs-update u:\os373py.zd at the "ok" prompt.
The machine is unsecured. All of the XO-1s I have have Developer Keys. Am I correct that a Developer Key is not needed for the XO-1.5?
So I am trying to do
it for an XO-1 instead. However, I notice that while there
are two files for the XO-1, the .img file and the .crc file,
there is only one for the XO-1.5, the .zd file.
When I installed 852
on both types of machines, there were 2 files for each. Is
there a file missing on the Dextrose page listed above? Can I
just use the fs.zip file from 852?
While I am asking, is
there a reason why the files for the XO-1 for 852 are .img and
fs.zip while those for Dextrose are .img and .crc? I am not a
whiz on file types so I haven't a clue why these would be
fs.zip is a security bundle, needed only for updating a system with
security enabled. fs.zip does not contain any actual filesystem
data; instead, it contains a much-shorter list of hash values that
represent the actual data, and a signature that authenticates that
fs.img is for XO-1 only. It contains raw data that goes verbatim
into the internal NAND FLASH inside the XO-1.
fs.crc, for XO-1 only, contains a list of check values that
represent the data in fs.img. Its purpose is to catch corrupted
fs.img files, which sometimes happen due to download problems or USB
stick errors. The checksum algorithm in fs.crc (CRC-32) is much
weaker than the hash algorithm used in fs.zip. CRC-32 is good
enough to catch accidental file corruption, but not strong enough to
prevent a determined attack.
fs.zd is a new format that was introduced for XO-1.5. It combines
checking (via the strong hash code) and the actual filesystem image
data in one file, with explicit compression to shrink the file to a
manageable size. It was necessary to come up with a new format
because XO-1 and XO-1.5 have very different internal storage. XO-1
uses raw NAND FLASH that is formatted with the JFFS2 filesystem
layout, while XO-1.5 uses a micro-SD card that emulates a hard disk,
formatted with the same ext2/ext4 filesystem layout. JFFS2
filesystem data is already internally compressed, so there is no
need for explicit compression. That is not the case for ext2
filesystem data, so the compression had to be explicit in the .zd
The fs.zip files for XO-1 and XO-1.5 are similar, but not
identical. For XO-1, fs.zip contains hash values suitable for
checking fs.img. For XO-1.5, fs.zip contains hash values too, but
their format is different, being suitable for checking fs.zd.
I need to get this
done in time for a "show and tell" at Montana State University
on Thursday morning.
Testing mailing list
Testing at lists.laptop.org
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