Hardware Reference
In-Depth Information
timization levels are not compatible with each other. On Linux, there is a
good way to check for support for ARMv6 hard-float, using the
readelf
command:
$ readelf -a /usr/lib/libc.so.6 | grep FP
You can run this command directly on the Raspberry Pi Linux distribution
(you might need to install the
elfutils
package first), or you can copy a
binary or library from within the Raspberry Pi Linux distribution and onto
another system with
readelf
handy.
If the binary has support for ARMv6 hard-float optimization, you will get
output that looks like this:
Tag_FP_arch: VFPv2
Tag_ABI_FP_rounding: Needed
Tag_ABI_FP_denormal: Needed
Tag_ABI_FP_exceptions: Needed
Tag_ABI_FP_number_model: IEEE 754
Tag_ABI_HardFP_use: SP and DP
Tag_ABI_VFP_args: VFP registers
The important line is the last one,
Tag_ABI_VFP_args: VFP registers
. It will
show up only if the binary being checked is built with ARMv6 hard-float
optimization.
Once you've installed it (if necessary), look at the options that
vcgencmd
offers:
$ vcgencmd commands
This will output a list of all the commands that you can pass to the
vcgencmd
tool:
commands="vcos, ap_output_control, ap_output_post_processing,
vchi_test_init, vchi_test_exit, pm_set_policy, pm_get_status,
pm_show_stats, pm_start_logging, pm_stop_logging, version, commands,
set_vll_dir, led_control, set_backlight, set_logging, get_lcd_info,
set_bus_arbiter_mode, cache_flush, otp_dump, codec_enabled, get_camera,
get_mem, measure_clock, measure_volts, measure_temp, get_config,
hdmi_ntsc_freqs, hdmi_status_show, render_bar, disk_notify, inuse_notify,
sus_suspend, sus_status, sus_is_enabled, sus_stop_test_thread, egl_plat
form_switch, mem_validate, mem_oom, mem_reloc_stats, file, vctest_memmap,
vctest_start, vctest_stop, vctest_set, vctest_get"
Unfortunately, it doesn't actually tell you anything about those commands or what
they do. Some of them seem obvious, but then when you run them, they return things
like this:
error=2 error_msg="Invalid arguments"
