Format Specifiers

%%

The percent sign (%) 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 question mark (?) 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'.

%H

Print the specified 64-bit signed integer with byte count value in human readable form (for example, 1345433533242 would print as 1.2T). The default format will use standard unit notation per SI for the unit letters. Alternately, you can use the %#H format to print all lower case letters.

%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.

%N

Dereference a pointer to a 128-bit value, convert it to network order, and reformat the value as an IPv6 address. If the value represents an IPv4 address, the value is formatted as follows:

Dotted-decimal format preceded by two colon characters (::) for IPv4 compatibility addresses
Dotted-decimal format preceded by ::ffff: for IPv4 mapped addresses

The value is formatted as eight 16-bit hexadecimal values that are separated by colon (:) characters.

The following list shows the network order and format of the various address types:

IPv4: Network order is 000000000000000000000000ffffffff and the format is ::255.255.255.255
IPv4 mapped: Network order is 00000000000000000000ffffffffffff and the format is ::ffff:255.255.255.255
IPv6: Network order is ffffffff0000ffff0000ffff0000ffff and the format is ffff:ffff:0:ffff:0:ffff:0:ffff

%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'.