c)lets say for a program a.c i use gcc -S a.c ...do we have some other command to generate
somewhat more clear assembly code, may be with some comments in english

Not sure if this is of any help, but the kernel build system (no idea how to do this for user space programs) offers to generate a listing that interleaves the c code into assembly making it better readable. So if your function is e.g. in kernel/rtmutex.c you could do the following:

andi@PC63:~/working_git/linux-next$ make kernel/rtmutex.lst
  SYSHDR  arch/x86/syscalls/../include/generated/uapi/asm/unistd_32.h
  SYSHDR  arch/x86/syscalls/../include/generated/uapi/asm/unistd_64.h
<SNIP>
  HOSTCC  scripts/asn1_compiler
  MKLST   kernel/rtmutex.lst
No System.map
andi@PC63:~/working_git/linux-next$

here is one function from the resulting rtmutex.lst file:

static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
{
  70:    e8 00 00 00 00           callq  75 <fixup_rt_mutex_waiters+0x5>
                                     71: R_X86_64_PC32    __fentry__+0xfffffffffffffffc
  75:    55                       push   %rbp
  76:    48 ff 05 00 00 00 00     incq   0x0(%rip)        # 7d <fixup_rt_mutex_waiters+0xd>
                                      79: R_X86_64_PC32    .bss+0x6fc
  7d:    48 89 e5                 mov    %rsp,%rbp
  80:    53                       push   %rbx
  81:    48 89 fb                 mov    %rdi,%rbx
                                           if (!rt_mutex_has_waiters(lock))
  84:    e8 8e ff ff ff           callq  17 <rt_mutex_has_waiters>
  89:    48 ff 05 00 00 00 00     incq   0x0(%rip)        # 90 <fixup_rt_mutex_waiters+0x20>
            8c: R_X86_64_PC32    .bss+0x704
  90:    85 c0                    test   %eax,%eax
  92:    75 0c                    jne    a0 <fixup_rt_mutex_waiters+0x30>
}

btw. you can for example generate the pre-processed code in the same way:

andi@PC63:~/working_git/linux-next$ make kernel/rtmutex.i

or the assembly code:

andi@PC63:~/working_git/linux-next$ make kernel/rtmutex.s

this is especially helpful, as it also contains a list of all the flags used for compiling.

regards,
andi


Any kind of help in understanding this will be appreciated ..

Thanks
Nidhi





--
Thanks & Regards
Nidhi Mittal Hada

http://nidhi-searchingmyself.blogspot.com/



_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies