Re: how to allocate 9MB of memory in kernel ?

[Marco Stornelli <marco.stornelli@coritel.it>]

Misbah khan ha scritto:
> Hi all,
> 
> I am getting kernel panic while trying these as suggested by you ,the
> following points will elaborate my concern :-
> 
> My circular buffer defination is this :-
> /* Frame */
> typedef struct
> {
> 	char buffer[SIZE_FRAME];
> 	unsigned int count;
> }frame_S;
> 
> /* Circular Buffer Structured */
> /* Mmaped area Structure */
> typedef struct
> {
> 
> 	frame_S  fluke[NO_FRAMES];
> 	unsigned int count_index;
> 	unsigned int read_index;
> 	unsigned int write_index;
> 
> }circularbuffer_S;
> 
> circularbuffer_S   *buf_area=NULL;
> 
> i am allocating memory using vmalloc and remaping to the SDRAM area as :-
> 
> buf_area = vmalloc(sizeof(circularbuffer_S));
> 	if(!buf_area)
> 	{
> 		printk(KERN_ALERT"vmalloc failed \n");
> 		return -1;
> 	}
> 
> 	buf_area = (circularbuffer_S *)ioremap(7700000,900000);

Here you are overwriting buf_area!!!!!

> 	if(!buf_area)
> 	{
> 		printk(KERN_ALERT"ioremap failed \n");
> 		return -1;
> 	}
> 
> 
> mmap Implimentation is this :-
> 
> unsigned long start = vma->vm_start;
> 	unsigned long size = vma->vm_end - vma->vm_start; //0x900000;
> 	unsigned long phy_add = virt_to_phys(buf_area); //0x7700000;
> 	int ret = 0;
> 
> 	/* Make the mmaped area noncacheable */
> 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> 
> 	/* Set the Flags to give permissions to Mmaped area */
> 	vma->vm_flags |=VM_RESERVED;
> 	vma->vm_flags |=VM_READ;
> 	vma->vm_flags |=VM_WRITE;
> 	vma->vm_flags |=VM_IO;
> 	//vma->vm_flags |=VM_SHARED;
> 	//vma->vm_flags |=VM_LOCKED;
> 
> 	printk(KERN_DEBUG"In mmap function\n");
> 
> 	if(remap_vmalloc_range(vma,buf_area,(phy_add >> PAGE_SHIFT)))
> 	{
> 		printk(KERN_ALERT"remap_vmalloc_range failed\n");
> 		goto mmap_exit;
> 
>    	}
> 
> I am getting mmap failed .....
> 
> some times i am getting this error .......
> 
> 
> /***************************************************/
> 
> insmod fluke_driver.ko
>  Ioremap mapped to virtual 0x0c7900e20
> Unable to handle kernel paging request at virtual address c8200e34
> pgd = c0444000
> [c8200e34] *pgd=85c80011, *pte=00000000, *ppte=00000000
> Internal error: Oops: 807 [#1]
> Modules linked in: fluke_driver tstamp sig_router mvci_spi mvci_sf_pcd
> mvci_sci_unidir_s1 mvci_sci_diff mvci_sci_bidir_s
> 1 g_ether mvci_rtmd_s1 mvci_kwiso_s1 mvci_kw1281_s1 mvci_kh_s1 mvci_j1850
> mvci_gm_sbc mvci_diagh_s1 mvci_dcl mvci_can1 f
> pga_conf arcotg_udc adc_dac keypad(F) splc501_lcd(F) cpld
> CPU: 0
> PC is at FlukeDriverInit+0xe4/0x140 [fluke_driver]
> LR is at preempt_schedule+0x48/0x58
> pc : [<bf01c0e4>]    lr : [<c0241e98>]    Tainted: GF
> sp : c69b9ed0  ip : c69b9e28  fp : c69b9eec
> r10: c7862000  r9 : 00000015  r8 : 00000016
> r7 : bf01aaa0  r6 : c682a5f0  r5 : bf01ac24  r4 : 00000000
> r3 : 00900014  r2 : c7900e20  r1 : c69b8000  r0 : 00000000
> Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  Segment user
> Control: C5387F
> Table: 80444000  DAC: 00000015
> Process insmod (pid: 1089, stack limit = 0xc69b8250)
> Stack: (0xc69b9ed0 to 0xc69ba000)
> 9ec0:                                     00000000 c682a5c4 c682a5c4
> c682a400
> 9ee0: c69b9fa4 c69b9ef0 c005ec78 bf01c00c 00000000 00000000 00011008
> 00000000
> 9f00: 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000
> 9f20: 00000000 00000000 00000000 00000000 c78642e8 c6aad200 c7863820
> c7863730
> 9f40: c7863848 00000000 0000006a 0000006a bf01aaac c00485d8 0000000a
> c69b8000
> 9f60: bf01aae8 c7863474 c7863870 00000013 00000000 c0282764 c69b9f9c
> 00008608
> 9f80: 00000003 00011018 00000080 c0020f64 c69b8000 00011008 00000000
> c69b9fa8
> 9fa0: c0020de0 c005d7d4 00008608 00000003 00011018 000025e8 00011008
> 0000002d
> 9fc0: 00008608 00000003 00011018 00000080 bec38f5e 00000000 00011008
> 00000000
> 9fe0: 00004000 bec38d14 000088dc 400db334 60000010 00011018 48010000
> 00000000
> Backtrace:
> [<bf01c000>] (FlukeDriverInit+0x0/0x140 [fluke_driver]) from [<c005ec78>]
> (sys_init_module+0x14b0/0x1698)
>  r5 = C682A400  r4 = C682A5C4
> [<c005d7c8>] (sys_init_module+0x0/0x1698) from [<c0020de0>]
> (ret_fast_syscall+0x0/0x2c)
> Code: eb408e00 e5952000 e59f3058 e1a00004 (e7824003)
>  Segmentation fault
> 
> /****************************************************/
> 
> Please suggest me what could be the problem and how to overcome this and do
> my implimentation ....
> 
> 
> ------Misbah <><
> 
> Arnd Bergmann wrote:
>> On Friday 18 July 2008, Misbah khan wrote:
>>
>>> Now my concern is How can i map SDRAM one to one to circular buffer of
>>> such
>>> a huge size ???? 
>> As I mentioned, use vmalloc to get the memory, and provide an mmap
>> function
>> that uses remap_vmalloc_range to put it into the user address space.
>>
>>> My idea is that i will ioreamp SDRAM and do memcpy_toio() when ever i am
>>> writing to the the circular buffer which is dma allocated and pages are
>>> set
>>> reserved . and read the frame from user space .
>> ioremap and memcpy_toio style accesses only make sense for stuff that is
>> *not* your main memory. Memory is alrady directly accessible in the kernel
>> after allocating with get_free_pages, kmalloc or vmalloc. No need to
>> play with __iomem pointers for this.
>>
>> 	Arnd <><
>> _______________________________________________
>> Linuxppc-embedded mailing list
>> Linuxppc-embedded@ozlabs.org
>> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
>>
>>
> 


-- 
Marco Stornelli
Embedded Software Engineer
CoRiTeL - Consorzio di Ricerca sulle Telecomunicazioni
http://www.coritel.it

marco.stornelli@coritel.it
+39 06 72582838