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Altera_Forum
Honored Contributor I
803 Views

Can I use 8M sdram for nios2-mmu linux?

hello, 

I have a custom fpga board with a ep2c20 core, a 8M cfi flash chip, a 8M sdram chip, etc.I design a smallest nios2 sopc with just a sdram controller, uart jtag and nios2-mmu with dual port on-chip memory, here are my dts info: 

see the 2c20_dts.txt attachment. 

here are my kernel configuration 

see the linux_config.txt attachment. 

It stucked in diffrent ways when I chose diffrent slab allocator, see the result for detail: 

1.slab: 

Linux version 3.1.0-rc4-01162-g45c9dd8 (liunx@gentoo) (gcc version 4.1.2)# 13 Fri Oct 7 14:12:07 CST 2011 bootconsole enabled early_console initialized at 0xe0000420 On node 0 totalpages: 8192 free_area_init_node: node 0, pgdat c132a2ac, node_mem_map c13387a0 DMA zone: 64 pages used for memmap DMA zone: 0 pages reserved DMA zone: 8128 pages, LIFO batch:0 pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768 pcpu-alloc: 0 Built 1 zonelists in Zone order, mobility grouping on. Total pages: 8128 Kernel command line: bootargs="debug console=ttyJ0,115200" PID hash table entries: 128 (order: -3, 512 bytes) Dentry cache hash table entries: 4096 (order: 2, 16384 bytes) Inode-cache hash table entries: 2048 (order: 1, 8192 bytes) Memory available: 29152k/3289k RAM (1017k kernel code, 2271k data) BUG: failure at /home/liunx/Work/Fpga/nios2-linux/linux-2.6/mm/slab.c:3111/cache_alloc_refill()! Kernel panic - not syncing: BUG! 2.slob 

PID hash table entries: 128 (order: -3, 512 bytes) Dentry cache hash table entries: 4096 (order: 2, 16384 bytes) Inode-cache hash table entries: 2048 (order: 1, 8192 bytes) Memory available: 29160k/3281k RAM (1011k kernel code, 2269k data) NR_IRQS:32  

The slob may work for my board, I traced the slob one, it stuck during the eary_irq_init() loop, I guess that may be the size of sdram is not fit the kernel's demand? 

And how many memory the kernel need with mmu support?:(
0 Kudos
7 Replies
Altera_Forum
Honored Contributor I
28 Views

Something is wrong with the way you've told the kernel about the amount of memory - 'Memory available 29160k/3281k' shows more available than the total size! 

I also suspect you need to shrink some kernel data areas in order to run anything useful in 8M - even the Dentry & Inode caches look a bit big, but the 2269k of kernel data is a huge fraction of your 8M. 

I'm not a Linux expert - so can't help on actually reducing the size.
Altera_Forum
Honored Contributor I
28 Views

Did You set the SDRAM address correctly? There are issues with that.

Altera_Forum
Honored Contributor I
28 Views

 

--- Quote Start ---  

Did You set the SDRAM address correctly? There are issues with that. 

--- Quote End ---  

 

Thanks very much for your tips, I should modify the nios.h of in the nios2/include/asm and then it works but I still have problem, see the result: 

... 

pid_max: default: 4096 minimum: 301 

Mount-cache hash table entries: 512 

������������������ 

... 

I got lots of "????", what's wrong with me again? 

thanks!
Altera_Forum
Honored Contributor I
28 Views

Do you have another board with more physical memory? 

Might be worth booting that one to see which messages are expected next. 

Also repeatedly cut down the reported amount of memory to see if it will run in 8MB. It is probably easier to reduce the memory footprint (which is probably your problem) on a working system!
Altera_Forum
Honored Contributor I
28 Views

I suggest You reading this blog: http://www.grigaitis.eu/?p=698 

Check SOPC builder addresses. SDRAM must be at 0x10000000 and all the other components must fit to lower addresses.
Altera_Forum
Honored Contributor I
28 Views

Thanks very much for your tips!

Altera_Forum
Honored Contributor I
28 Views

 

--- Quote Start ---  

I suggest You reading this blog: http://www.grigaitis.eu/?p=698 

Check SOPC builder addresses. SDRAM must be at 0x10000000 and all the other components must fit to lower addresses. 

--- Quote End ---  

 

Thanks very much for your links!