Tags
ASCII, cheatsheet, core, crashdump, dbx, dbx command, Debugging, Solaris
To get the next 10 locations from an address X..
(dbx) x 0xa848410 /10X 0x0a848410: 0x00920f50 0x0aa5e2d0 0x0a0ad868 0x0000081b 0x0a848420: 0x00000015 0x3a10bfeb 0x41424346 0x46463033
the caps X provides the word alignment .
Understanding the layout of examine (x) command..
The examine command, examines the memory locations with the interval of 0x10 i.e decimal 16.
It presents in a matrix format, with 4 columns. Each column is 4 bytes wide so every row is in interval of 4 * 4 i.e 16 bytes which is 0x10 in Hex.
Consider a examine as follows..
(dbx) x 0x0c2c0088 /10X 0x0c2c0088: 0x13db0570 0x00000000 0x0e92e268 0x00000000 0x0c2c0098: 0x0a398158 0x13db7920 0x00e8b0d0 0x00000000 0x0c2c00a8: 0x00000000 0x00000000
In the first row,
0x0e92e268
is in the 3rd column in first row, which is starting at address
0x0c2c0088
Applying the above matrix math, one can understand that
0x0e92e268
is in address
0xc2c0090
which is at 8 bytes from the starting address of the row. So if we examine what is in the location
0xc2c0090
we get the output as…
(dbx) x 0xC2C0090 0x0c2c0090: 0x0e92e268
To read ASCII
(dbx) x 0x0a1f91e5 /s 0x0a1f91e5: "This is a sample text"
To read the static symbols in corefile, even in release mode binaries / core..
All static symbols can be read by DBX even if it is in the release mode.
static MyClass* theClass;
(dbx) x theClass 0x00f06198: 0x0c2c0088
To map the structure / class members with a memory location in corefile..
The structure / class members can be easily mapped with the examine command as follows.
Consider the following structure…
struct MyContext{
unsigned long* links; unsigned long* links_prev;
unsigned long interpLevel;
unsigned long stackLimit;
/* Runtime version control identifier and equality operators. */
unsigned long version;
byte op_eq;
byte op_ne;
/* Data shared by threads in an address space. */
void *runtime;
};
and in the core, let us try too map the offsets with the structure. Consider that
0xa533248
is pointing to a instance of MyContext structure.
(dbx) x 0xa533248 /10X 0x0a533248: 0x0a532f48 0x0a533548 0x00000002 0x00000000 0x0a533258: 0x00000000 0x12130000 0x00ad6808 0x00c05408
which can be understood as follow.
</pre> 0x0a532f48 = pointer to links. 0x0a533548 = pointer to links_prev. 0x00000002 = interpLevel. 0x00000000 = stacklimit. 0x00000000= version.
and so on…
will update this post, as and when I find some more information, worthy to be shared w.r.t DBX.
kspviswa 