Mailing List Archive

Problem with bootmem/mmap
Dear all,
I'm allocating a large buffer at boot time (for later DMA purposes) using:
buf=alloc_bootmem_low_pages(1024*1024*500);
If I printk here, from init/main.c, I get:
buf=0xc1e14000
__va(buf)=0x81e14000
__pa(buf)=0x1e14000
Now, in user-space, I'm trying to get access to my buffer (as root), by
doing the following:
memfd=open("/dev/mem", O_RDWR);
my_buf=mmap(0, 1024*1024*501, PROT_READ|PROT_WRITE,
MAP_SHARED|MAP_FIXED, memfd, OFFSET);
I've tried all those addresses above, as the OFFSET, but it either generates
an illegal instruction,
or a segfault. Bit of a beginner, but learning fast, and I'd be _really_
greatful, if anyone could help me!
Many thanks,
Ed
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