Format Specifiers

%%

The '%' symbol is printed.

%a

Prints an address in symbolic form. The minimum size of the value associated with %a is a uintptr_t; specifying %la is not necessary. If address-to-symbol conversion is on, the debugger will attempt to convert the address to a symbol name followed by an offset in the current output radix and print this string; otherwise, the value is printed in the default output radix. If %#a is used, the alternate format adds a ':' suffix to the output.

%A

This format is identical to %a, except when an address cannot be converted to a symbol name plus an offset, nothing is printed. If %#A is used, the alternate format prints a '?' when address conversion fails.

%b

Decode and print a bit field in symbolic form. This specifier expects two consecutive arguments: the bit field value (int for %b, long for %lb, and so forth), and a pointer to an array of mdb_bitmask_t structures:

typedef struct mdb_bitmask {
        const char *bm_name;       /* String name to print */
        u_longlong_t bm_mask;      /* Mask for bits */
        u_longlong_t bm_bits;      /* Result for value & mask */
} mdb_bitmask_t;

The array should be terminated by a structure whose bm_name field is set to NULL. When %b is used, the debugger reads the value argument, then iterates through each mdb_bitmask structure checking to see if:

(value & bitmask->bm_mask) == bitmask->bm_bits

If this expression is true, the bm_name string is printed. Each string printed is separated by a comma. The following example shows how %b can be used to decode the t_flag field in a kthread_t:

const mdb_bitmask_t t_flag_bits[] = {
        { "T_INTR_THREAD", T_INTR_THREAD, T_INTR_THREAD },
        { "T_WAKEABLE", T_WAKEABLE, T_WAKEABLE },
        { "T_TOMASK", T_TOMASK, T_TOMASK },
        { "T_TALLOCSTK", T_TALLOCSTK, T_TALLOCSTK },
        /* ... */
        { NULL, 0, 0 }
};

void
thr_dump(kthread_t *t)
{
        mdb_printf("t_flag = <%hb>\n", t->t_flag, t_flag_bits);
        /* ... */
}

If t_flag was set to 0x000a, the function would print:

t_flag = <T_WAKEABLE,T_TALLOCSTK>

If %#b is specified, the union of all bits that were not matched by an element in the bitmask array is printed as a hexadecimal value following the decoded names.

%c

Print the specified integer as an ASCII character.

%d

Print the specified integer as a signed decimal value. Same as %i. If %#d is specified, the alternate format prefixes the value with '0t'.

%e

Print the specified double in the floating-point format [+/-]d.ddddddde[+/-]dd, where there is one digit before the radix character, seven digits of precision, and at least two digits following the exponent.

%E

Print the specified double using the same rules as %e, except that the exponent character will be 'E' instead of 'e'.

%g

Print the specified double in the same floating-point format as %e, but with sixteen digits of precision. If %llg is specified, the argument is expected to be of type long double (quad-precision floating-point value).

%G

Print the specified double using the same rules as %g, except that the exponent character will be 'E' instead of 'e'.

%i

Print the specified integer as a signed decimal value. Same as %d. If %#i is specified, the alternate format prefixes the value with '0t'.

%I

Print the specified 32-bit unsigned integer as an Internet IPv4 address in dotted-decimal format (for example, the hexadecimal value 0xffffffff would print as 255.255.255.255).

%m

Print a margin of whitespace. If no field is specified, the default output margin width is used; otherwise, the field width determines the number of characters of white space that are printed.

%o

Print the specified integer as an unsigned octal value. If %#o is used, the alternate format prefixes the output with '0'.

%p

Print the specified pointer (void *) as a hexadecimal value.

%q

Print the specified integer as a signed octal value. If %#o is used, the alternate format prefixes the output with '0'.

%r

Print the specified integer as an unsigned value in the current output radix. The user can change the output radix using the $d dcmd. If %#r is specified, the alternate format prefixes the value with the appropriate base prefix: '0i' for binary, '0o' for octal, '0t' for decimal, or '0x' for hexadecimal.

%R

Print the specified integer as a signed value in the current output radix. If %#R is specified, the alternate format prefixes the value with the appropriate base prefix.

%s

Print the specified string (char *). If the string pointer is NULL, the string '<NULL>' is printed.

%t

Advance one or more tab stops. If no width is specified, output advances to the next tab stop; otherwise the field width determines how many tab stops are advanced.

%T

Advance the output column to the next multiple of the field width. If no field width is specified, no action is taken. If the current output column is not a multiple of the field width, white space is added to advance the output column.

%u

Print the specified integer as an unsigned decimal value. If %#u is specified, the alternate format prefixes the value with '0t'.

%x

Print the specified integer as a hexadecimal value. The characters a-f are used as the digits for the values 10-15. If %#x is specified, the alternate format prefixes the value with '0x'.

%X

Print the specified integer as a hexadecimal value. The characters A-F are used as the digits for the values 10-15. If %#X is specified, the alternate format prefixes the value with '0X'.

%Y

The specified time_t is printed as the string 'year month day HH:MM:SS'.