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PostPosted: Wed Oct 03, 2007 4:36 am 
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Joined: Tue Oct 02, 2007 7:22 pm
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The KuroBox Pro got larger Flash on the system. Is it possible to install all linux system into flash. The HD only have swap & data storage?

The manual teach us how to install the system & boot from HD. If I make a swap for the system. it is possible damage NAND flash when system run?

Would I must install systeom on the HD?


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PostPosted: Wed Oct 03, 2007 6:52 am 
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Joined: Fri Oct 29, 2004 6:00 am
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Location: UK
The Wiki page says "256Mb flash", so in theory it may be possible.

Would you want to run with the filesystem inside flash, or just store an initrd in flash? If the initrd is in flash, then you'd use a lot of the normal system ram to hold the uncompressed root filesystem...

I don't know whether it'd be possible to use a root filesystem directly from flash.


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PostPosted: Wed Oct 03, 2007 7:57 am 
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Lardmonster wrote:
The Wiki page says "256Mb flash", so in theory it may be possible.

Would you want to run with the filesystem inside flash, or just store an initrd in flash? If the initrd is in flash, then you'd use a lot of the normal system ram to hold the uncompressed root filesystem...

I don't know whether it'd be possible to use a root filesystem directly from flash.


I am not sure about what is run with the filesystem inside flash? Is it not the same as a root filesystem directly from flash?

When I installed the HD in the Kuro-Box Pro, I can telnet to Kuro-box pro then mount the HD on the filesystem. I am not sure what is the EM mode at this time?


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PostPosted: Thu Oct 04, 2007 7:02 am 
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Joined: Fri Oct 29, 2004 10:08 am
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Location: MA
256 MB is Plenty of room to run from FLASH. You have to do a bit of thinking and not install a lock stock whole distro, but you can get everything you need in 256 MB easy.

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Thanks
Brian


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PostPosted: Thu Oct 04, 2007 10:13 am 
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Joined: Wed Sep 26, 2007 6:12 pm
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How fast it will be? Any one have a idea?
It is better to run in flash or from HDD, I am talk about speed here.


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PostPosted: Fri Oct 05, 2007 6:14 am 
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Joined: Mon May 30, 2005 9:01 am
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Location: France, St Cyr-L'Ecole (78)
For now, a HDD are faster than flash, but don't forget that all that is running in your system is in RAM, so the startup may be a little bit longer if running from flash (few seconds of difference I guess), but after that you will see no difference (as your data will be in the HDD).
An important thing to do when running from flash is to set-up a ramdisk so all system logs will be stored in RAM and not in flash (to prevent your flash from beeing dead after few years of 24h/24 usage). To reduce problems, you may want to use a NAND Flash optimized filesystem (YAFFS2 seems to be great for that but you'll need to patch the kernel to add it : http://www.yaffs.net/ ). Another solution is to use JFFS2 which is slower on NAND memory but is compressing the system (slowing down the system speed when accessing the JFFS2 partition).

You should also read that for informations about NAND & Linux usage :
http://www.linux-mtd.infradead.org/faq/general.html
http://www.linux-mtd.infradead.org/faq/nand.html
http://www.linux-mtd.infradead.org/faq/jffs2.html


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PostPosted: Fri Oct 05, 2007 8:04 am 
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Joined: Wed Sep 26, 2007 6:12 pm
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Thanks Sylver, so I will boot from HDD, as it is safer and faster.
I can't wait saturday to install my system.


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PostPosted: Fri Oct 05, 2007 8:36 am 
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FLASH and JFFS2 is very nice for many things. If you have a readonly root. FLASH will be faster than DISK. FLASH read time is very fast and seek time is 0. Also JFFS2s sector caching makes subsequent reads even faster. I have booted systems with a full SYSVinit layer in 30 seconds. The trick is basically if you want to use FLASH you need to think about your problemand partitionit sanely. make /var a ramdisk, make your root filesystem typically read only, and put your data on disk. This is actually a really nice NAS solution because the disk ONLY holds data. The OS can remain with the hardware and inserting a new disk can be simply formatted and mounted.

If all of this sounds like work, then don't bother. disk is typically fast enough so unless the challenge excites you, don't bother.
BTW System on FLASH is a very good skill if you want to end up doing embedded Linux development as a carreer and the KuroPro is a good starting point because the CPU speed and FLASH size make little mistakes forgivable.
Anyone wanting to talk in more detail about embeddded system desgin let me know. We will move it to a new thread.

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Hint of the day: See pages added to the wiki via RSS: http://www.kurobox.com/mwiki/index.php? ... s&feed=rss



Thanks

Brian


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PostPosted: Sat Oct 06, 2007 12:54 am 
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Joined: Mon May 30, 2005 9:01 am
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Location: France, St Cyr-L'Ecole (78)
Embedeed products are sometimes using CRAMFS (that is a readonly FS) once developments are finished and that the product is ready for market ;)
BTW, where to find the flash memory contents ? I guess it's in mtd? but I don't want to crash the U-Boot code for now, so, is the flash mapping known and described somewhere ?
I'd like to benchmark the speed on it ;)
I've read that there are 2 flash in the kurobox pro (256KB of NOR flash and 256MB of NAND flash), what is the NOR flash used for (256KB is so small) and how to access it ?
Thanks,
Sylver :)


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PostPosted: Tue Oct 09, 2007 11:19 am 
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Joined: Fri Mar 18, 2005 7:34 am
Posts: 56
Location: UK
I think it is. I have looked on mine and I think that it is in a clearly defined area. Will double check though.

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PostPosted: Wed Oct 10, 2007 4:02 pm 
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Joined: Mon May 30, 2005 9:01 am
Posts: 279
Location: France, St Cyr-L'Ecole (78)
Ok, /dev/mtd0 is for u-boot, mtd1 is for kernel in flash, mtd2 for rootfs and mtd3 is user space (around 250MB) ;) So don't touch /dev/mtd0


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