2009-01-16 03:28:15     uCLinux executing from SD-Card or Flash

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2009-01-16 03:28:15     uCLinux executing from SD-Card or Flash

Patrick Hotz (GERMANY)

Message: 68011   

 

Hello everybody,

 

Soon after my uCLinux-dist2009pre was running i think there is a big problem with free RAM.....

If the uCLinux runs from a RAM-Disk with 15Mb the free RAM reduced to 17Mb. That is to little for my applications...

 

I have read in the Kernel-Config that the uCLinux is able to executes from RAM or ROM.

My question is how can i configure the uClinux to execute from Flash or better the SD-Card?

 

I want to keep the whole 32Mb RAM free for my applications......

 

 

 

Regards

- Patrick

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2009-01-16 04:31:42     Re: uCLinux executing from SD-Card or Flash

Michael Heiser (GERMANY)

Message: 68025   

 

Hey guys,

 

I Think the whole RAM cannot be used for your programs. The solution for this problem would be to emulate a swap space on your flash or the SD-Card.

 

But how you can emulate SWAP i dunno...

 

Perhaps anyone of the Pros here

 

Regards Michael

 

 

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2009-01-16 13:10:11     Re: uCLinux executing from SD-Card or Flash

Mike Frysinger (UNITED STATES)

Message: 68039   

 

XIP does not work for the kernel or userspace.  you can run your rootfs out of a SD card, but the programs/libraries would still be copied to RAM before running.

 

also, the only thing you can ever do XIP with would be things that are directly addressable.  that means parallel flash only.

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2009-01-16 13:19:29     Re: uCLinux executing from SD-Card or Flash

Mike Frysinger (UNITED STATES)

Message: 68041   

 

to be clear, XIP support is currently not implemented or is broken for Blackfin/no-mmu Linux.  we're working on it and hopefully userspace XIP should be working again with 2009R1 final.  kernel XIP is planned for 2009R2.

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2009-01-18 12:51:16     Re: uCLinux executing from SD-Card or Flash

Patrick Hotz (GERMANY)

Message: 68069   

 

That means that the programms i want to execute will always first be copied into Ram before they are running?

 

My idea is that i compile the programms which needs the QT-Librarys with "-static" (means the library into the programm) and save them on my SD-Card. So i can set the Ram-Disk very much smaller.....

 

Also i have found a adjustment in Kernel-Konfig which i can say "Kernel executes from... RAM or ROM"

If i have a uClinux-Filesystem like the Ram-Disk now which is smaller than 8MB (thats the size of my flash) can i boot from flash directly?

 

Is that possible?

 

- Patrick

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2009-01-18 13:06:05     Re: uCLinux executing from SD-Card or Flash

Mike Frysinger (UNITED STATES)

Message: 68071   

 

if the storage is not directly addressable, then the code/data must first be copied to RAM.  there is absolutely no way around that.

 

as for the kernel option you mention, i already explained current status of XIP support.

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2009-01-18 15:26:56     Re: uCLinux executing from SD-Card or Flash

Patrick Hotz (GERMANY)

Message: 68073   

 

Hi Mike,

 

thank you for the answers...

I was not shure that XIP and "Kernel executes...." means the same.

I will have a try with the "-static" option for my programms...

 

Regards

- Patrick

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2009-01-18 15:41:24     Re: uCLinux executing from SD-Card or Flash

Mike Frysinger (UNITED STATES)

Message: 68075   

 

yes, XIP generally only applies to read only memory (ROM) as it's pretty hard to do XIP with changing memory since the read-only regions (.text) needs to be contiguous on nommu

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2009-01-18 23:22:08     Re: uCLinux executing from SD-Card or Flash

Sonic Zhang (CHINA)

Message: 68078   

 

XIP from NOR flash is not supported in last release and next 09R1 release.

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