On 9/12/2010 5:09 PM, Caryl Bigenho wrote:
------------------------------------------------------------------------------------------------------------------------
Date: Sun, 12 Sep 2010 16:41:34 -1000
From: [email protected]
To: [email protected]
CC: [email protected]; [email protected]; [email protected]
Subject: Re: [Testing] Dextrose Install Snags
On 9/12/2010 4:12 PM, Caryl Bigenho wrote:
Hi...
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./|
Is the message like "WARNING: The file specified N chunks but wrote only M
chunks"?
"The file was all in one chunk" is not a particularly close approximation ...
The warning message shown above typically indicates that the .zd file is
truncated, missing parts at the end.
/
/
/||//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?/
Whether or not a developer key is needed does not depend on XO-1 vs XO-1.5, but rather how the individual machine is
configured at the factory. XO-1 and XO-1.5 systems can both have security either enabled or disabled.
/
/
/Caryl/
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 different.
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 hash list.
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 file format.
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.
Thanks,
Caryl
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