Por alguma razão, minhammap falhou com umInvalid argument mensagem mesmo que meu deslocamento esteja alinhado à página. O tamanho da página é 4096 bytes. Além dissoCONFIG_STRICT_DEVMEM está desativado, ou seja, consigo acessar a memória acima de 1 MB.

Aqui está o meu código:

void *mmap64;
off_t offset = 0x000000d9fcc000;
int memFd = open("/dev/mem", O_RDWR);
if (-1 == memFd)
  perror("Error ");

mmap64 = mmap(0, getpagesize(), PROT_WRITE | PROT_READ, MAP_SHARED, memFd, offset);
if (MAP_FAILED == mmap64) {
  perror("Error ");
  return -1;
}

Alguém pode explicar por que isso está acontecendo?

EDITAR

Aqui está ostrace do meu código

execve("./to_phys_test", ["./to_phys_test", "-r"], [/* 18 vars */]) = 0
brk(0)                                  = 0x2012000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe240a2c000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=162063, ...}) = 0
mmap(NULL, 162063, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fe240a04000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P \2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1840928, ...}) = 0
mmap(NULL, 3949248, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fe240447000
mprotect(0x7fe240601000, 2097152, PROT_NONE) = 0
mmap(0x7fe240801000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1ba000) = 0x7fe240801000
mmap(0x7fe240807000, 17088, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fe240807000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe240a03000
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe240a01000
arch_prctl(ARCH_SET_FS, 0x7fe240a01740) = 0
mprotect(0x7fe240801000, 16384, PROT_READ) = 0
mprotect(0x601000, 4096, PROT_READ)     = 0
mprotect(0x7fe240a2e000, 4096, PROT_READ) = 0
munmap(0x7fe240a04000, 162063)          = 0
open("/dev/mem", O_RDWR)                = 3
open("/dev/my_kmodule", O_RDWR)    = 4
ioctl(4, 0x40086e00, 0x7ffc72b334b0)    = 0
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe240a2b000
write(1, "sa.size = 44\n", 13)          = 13
write(1, "sa.addr_uint64_t = d9047000\n", 28) = 28
write(1, "sa.addr_void_ptr = 0xd9047000\n", 30) = 30
write(1, "PAGE_SIZE = 4096\n", 17)      = 17
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0xd9047000) = -1 EINVAL (Invalid argument)
dup(2)                                  = 5
fcntl(5, F_GETFL)                       = 0x8002 (flags O_RDWR|O_LARGEFILE)
brk(0)                                  = 0x2012000
brk(0x2033000)                          = 0x2033000
fstat(5, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fe240a2a000
lseek(5, 0, SEEK_CUR)                   = -1 ESPIPE (Illegal seek)
write(5, "Error : Invalid argument\n", 25) = 25
close(5)                                = 0
munmap(0x7fe240a2a000, 4096)            = 0
exit_group(-1)                          = ?
+++ exited with 255 +++