5 sec boot
wmb at laptop.org
Sun Oct 5 14:36:15 EDT 2008
> When I will finally have some time (currently I am working even on
> weekends) I will finish my half made zlib decompression code.
To what end? AFAIK the zlib decompression (both in OFW and in the OS)
is not one of the primary problem areas.
> Where is that Security hash's code?
The computation code is at http://dev.laptop.org/git?p=bios-crypto . It
is based on LibTomCrypt.
The specific hashes and signatures that we use are detailed in the
"Computation" column of http://wiki.laptop.org/go/Firmware_security#Summary
The security computation code has undergone an audit by outside security
experts. Any changes to the core code would require an additional audit.
> Mitch Bradley wrote:
>> Memory to memory copy: 500 MB/s
>> Raw NAND FLASH read: 20 MB/s
>> Security hash: 4 MB/s
>> So overlapping hash calculation with NAND FLASH read is of limited
>> value, and trying to overlap anything with memory copy is almost
>> certainly counterproductive.
>> This discussion seem to be degenerating into a brainstorming session
>> about an sub-problem that is pretty well under control (the firmware
>> component of the boot time). I've been working diligently on that
>> sub-problem for nearly 2 years now, and I think I have an excellent
>> grasp of where the cycles are going and what can be done to improve
>> it. The only significant opportunity at this point is to reduce the
>> JFFS2 time, which will require either partitioning or abandoning
>> JFFS2 for the boot files, or both. UBI+UBIFS is one workable
>> approach in the context of a Linux-only machine. There are some
>> others, such as Redboot partitions with a small boot partition and a
>> large system partition, with various FS possibilities for the two
>> partitions. The quickest path to a deliverable system would be
>> Redboot + JFFS2 boot partition + UBI system partition.
>> The rest of the "fruit" on the tree is solidly in the OS domain,
>> encompassing kernel startup, userland startup/initscripts, X startup,
>> and Sugar / application startup. I would encourage each of you to
>> address the areas in which you have special expertise, and then to
>> take action.
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