Memory Mapping failed. Error: 1

[freddyglima]

Hello everyone!
So, I was working with Ubuntu 9.10 and I wrote a C program which was working just fine. Then, I have installed Ubuntu 10.10 and tried to run this same program again. However, I get the following error:

Memory Mapping failed. Error: 1

Part of the code has the following:

volatile ulong *memory;

int fd = open("/dev/mem", O_RDWR | O_SYNC);

	if (fd < 0) {						
		printf("Could not open memory.\n");
		return(0);
	}


// Memory address to save data
	ulong address2;
	address2 = 0x80F00000;	

// Memory access
	memory = (ulong*) mmap(NULL, 0x10000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, (address2 & 0xFFFF0000));
	if (memory == MAP_FAILED) {
		printf("Memory Mapping failed. Error: %d.\n", errno);
		close(fd);
		return(0);
	}

I have seen that "errno=1" means an operation not permitted but I can not see where that could happen.

I have reduced the 0x10000 to 0x1000, changed the name "memory" to "memoria" and changed "(address2 & 0xFFFF0000)" to "address2". However, the same error persists.

I have also something similar in this same program and it is working fine:

#define PIN_CONF	0x48000000
volatile ulong *pinconf;

// Pad configuration							
pinconf = (ulong*) mmap(NULL, 0x10000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, PIN_CONF);  //0x10000 are the 4KB adressed to the mem.
	if (pinconf == MAP_FAILED) {
		printf("Pinconf Mapping failed. Error: %d.\n", errno);
		close(fd);					
		return(0);
	}

Does anyone have an idea what the problem could be? I do not know if there would be any significant change between Ubuntu 9.10 and 10.10 that could be generating me this problem.

Thanks in advance!
Frederico

[freddyglima]

Apparently, this new version of Linux reserves some memory addresses which the older one did not. So, if I find another memory address which has not been used, it might work.
However, it is weird that I can not access a large range of memory addresses which I could access with the older Linux Version.

[freddyglima]

I have changed the address from 0x80F00000 to 0xE0C00000 and it works...

[Rubberman]

One thing you have to remember is that you have to map memory at page boundaries. Each page is 4096 (4K) bytes.