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Altera_Forum
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13 years ago

Can I upload Nios2 SMP system?

Hi, guys & Altera corp. I'm now making a Nios2 SMP system for my research purpose. It's still a little bit buggy and slow, but I succeeded to boot Linux kernel and execute bash. Linux ...
Altera_Forum's avatar
Altera_Forum
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13 years ago

Hi,

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But how did you handle cache synchronization and the inter-CPU atomic operations that are necessary to do the Mutex API and the multiple Kernel-internal synchronization issues ?

(I understand that this is close to impossible without modifying the CPU design.)

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At first, I removed the normal data cache from the Nios2/f core (select the data cache <none> option in the SOPC builder) and added my original 1st (write-through) data cache. The cache synchronization method is the same one that is used in the clone's case. For atomic memory operations, I implemented the 'swap' that is controlled as a custom instruction. Unfortunately, we can't use cache non-cache information outside of Nios2 core, so I changed the kernel memory mapping like 


0xc0000000-0xcfffffff  : cacheable
0xd0000000-0xdfffffff  : non-cacheable
0xe0000000-0xefffffff  : cacheable
0xf0000000-0xffffffff  : non-cacheable
.

Kazu