Thanks for your replying. Still I am not clear in a
below output, that If we are loading shared object
librt in a memory map, then why are we calling unmmap
before we make a call to the functions exposed by
litrt e.x rt_sigaction.
Could you explain at what time a context switch takes
place from user space to a kernel space. The function
call gettimeofday is being executed in a user space as
it is not a kernel sys call, so at what point a switch
takes place. How is responsible for switching from
user to kernel and vice versa and I would like to see
that code.
Please give your views over this.
Regards
Dinesh
open("/lib/librt.so.1", O_RDONLY) = 3
read(3,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0D\32\0\000"...,
1024) =
1024
fstat64(3, {st_mode=S_IFREG|0755, st_size=33092, ...})
= 0
old_mmap(NULL, 69784, PROT_READ|PROT_EXEC,
MAP_PRIVATE, 3, 0) = 0x4009b000
mprotect(0x400a1000, 45208, PROT_NONE) = 0
old_mmap(0x400a1000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED, 3, 0x5000) = 0x400a1000
old_mmap(0x400a2000, 41112, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) =
0x400a2000
close(3) = 0
open("/lib/libc.so.6", O_RDONLY) = 3
read(3,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\350T\1"...,
1024) = 1024
fstat64(3, {st_mode=S_IFREG|0755, st_size=1481836,
...}) = 0
old_mmap(NULL, 1198532, PROT_READ|PROT_EXEC,
MAP_PRIVATE, 3, 0) = 0x400ad000
mprotect(0x401cc000, 22980, PROT_NONE) = 0
old_mmap(0x401cc000, 12288, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED, 3, 0x11e000) = 0x401cc000
old_mmap(0x401cf000, 10692, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) =
0x401cf000
close(3) = 0
munmap(0x40013000, 83287) = 0
getrlimit(0x3, 0xbfffeffc) = 0
setrlimit(RLIMIT_STACK, {rlim_cur=2044*1024,
rlim_max=RLIM_INFINITY}) = 0
getpid() = 1091
rt_sigaction(SIGRTMIN, {0x40052a2c, [], SA_RESTORER,
0x400d3bc8}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0x40052914, [], SA_RESTORER,
0x400d3bc8}, NULL, 8) = 0
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