[Testing] Dextrose Install Snags

[Mitch Bradley]

On 9/12/2010 5:09 PM, Caryl Bigenho wrote:
>
>
> ------------------------------------------------------------------------------------------------------------------------
> 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:
>
>     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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