how to press F1

[cckp]

The values for special keys such as Ctrl-B and F12 are defined in include/ipxe/keys.h within the iPXE source code.

keys.h:
http://git.ipxe.org/ipxe.git/blob/HEAD:/...pxe/keys.h

...
#define KEY_DC KEY_ANSI ( 3, '~' ) /**< Delete */
73 #define KEY_PPAGE KEY_ANSI ( 5, '~' ) /**< Page up */
74 #define KEY_NPAGE KEY_ANSI ( 6, '~' ) /**< Page down */
75 #define KEY_F5 KEY_ANSI ( 15, '~' ) /**< F5 */
76 #define KEY_F6 KEY_ANSI ( 17, '~' ) /**< F6 */
77 #define KEY_F7 KEY_ANSI ( 18, '~' ) /**< F7 */
78 #define KEY_F8 KEY_ANSI ( 19, '~' ) /**< F8 (for PXE) */
79 #define KEY_F9 KEY_ANSI ( 20, '~' ) /**< F9 */
80 #define KEY_F10 KEY_ANSI ( 21, '~' ) /**< F10 */
81 #define KEY_F11 KEY_ANSI ( 23, '~' ) /**< F11 */
82 #define KEY_F12 KEY_ANSI ( 24, '~' ) /**< F12 */
83
84 /* Not in the [KEY_MIN,KEY_MAX] range; terminals seem to send these as
85 *
...


only keys from F5 to F12 are defined

is F1 not supported ? or not recommend?

if it IS supported, you must build it from source and add that parameter to find the keycode?