--clock
options described here are supported on embedded
processor platforms and
Alveo™
platforms with
fixed clocks, as described in Managing Clock Frequencies. You can specify the --clock
option
using either a clock ID from the platform shell, or by specifying a frequency for the
kernel clock. When specifying the clock ID, the kernel frequency is defined by the
frequency of that clock ID on the platform. When specifying the kernel frequency, the
platform attempts to create the specified frequency by scaling one of the available
fixed
platform clocks. In some cases, the clock
frequency can only be achieved in some approximation, and you can specify the --clock.tolerance
or --clock.default_tolerance
to indicate an acceptable range. If the
available fixed clock cannot be scaled within the acceptable tolerance, a warning is
issued and the kernel is connected to the default clock.
The --clock.XXX
options provide a
method for assigning clocks to kernels from the v++
command line and locating the required kernel clock frequency source during the linking
process. There are a number of options that can be used with increasing specificity. The
order of precedence is determined by how specific a clock option is. The rules are
listed in order from general to specific, where more specific rules take precedence over
general rules:
- When no
--clock.XXX
option is specified, the platform default clock is applied to each compute unit (CU). For kernels with two clocks, clock ID 0 from the platform is assigned toap_clk
, and clock ID 1 is assigned toap_clk_2
. - Specifying
--clock.defaultId=<id>
defines a specific clock ID for all kernels, overriding the platform default clock assignments. - Specifying
--clock.defaultFreqHz=<Hz>
defines a specific clock frequency for all kernels that overrides a user specified default clock ID, and the platform default clock. - Specifying
--clock.id=<id>:<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
assigns a clock ID to a list of associated CUs, and optionally the clock pin for the CU. - Specifying
--clock.freqHz=<Hz>:<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
assigns the specified clock frequency to a list of associated CUs, and optionally the clock pin for the CU.
--clock.defaultFreqHz
--clock.defaultFreqHz <arg>
Specifies a default clock frequency in Hz to use for all kernels.
This lets you override the default platform clock and assign the specified clock
frequency as the default. <arg>
is
specified as the clock frequency in Hz.
For example:
v++ --link --clock.defaultFreqHz 300000000
[clock]
section head using the following format:
[clock]
defaultFreqHz=300000000
--clock.defaultId
--clock.defaultId <arg>
--clock.defaultId=<id>
defines a specific clock ID for all
kernels, overriding the platform default clock. <arg>
is specified as the clock ID from one of the clocks
defined on the target platform, other than the default clock ID. platforminfo -v
command as
described in platforminfo Utility. For example:
v++ --link --clock.defaultId 1
[clock]
section head using the following format:
[clock]
defaultId=1
--clock.defaultTolerance
--clock.defaultTolerance <arg>
Specifies a default clock tolerance as a value, or as a percentage
of the default clock frequency. When specifying clock.defaultFreqHz
, you can also specify the tolerance with either a
value or percentage. This updates the timing constraints to reflect the accepted
tolerance.
The tolerance value, <arg>, can be specified as a whole
number, indicating the clock.defaultFreqHz
± the
specified tolerance; or as a percentage of the default clock frequency specified as
a decimal value.
For example:
v++ --link --clock.defaultFreqHz 300000000 --clock.defaultTolerance 0.10
[clock]
section head using the following format:
[clock]
defaultTolerance=0.10
--clock.freqHz
--clock.freqHz <arg>
Specifies a clock frequency in Hz and assigns it to a list of
associated compute units (CUs) and optionally specific clock pins on the CU. <arg>
is specified as <frequency_in_Hz>:<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
:
-
<frequency_in_Hz>
- Defines the clock frequency specified in Hz.
-
<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
- Applies the defined frequency to the specified CUs, and optionally to the specified clock pin on the CU.
v++ --link --clock.freqHz 300000000:vadd_1,vadd_3
[clock]
section head using the following format:
[clock]
freqHz=300000000:vadd_1,vadd_3
--clock.id
--clock.id <arg>
Specifies an available clock ID from the target platform and
assigns it to a list of associated compute units (CUs) and optionally specific clock
pins on the CU. <arg>
is specified as
<reference_ID>:<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
:
-
<reference_ID>
- Defines the clock ID to use from the target platform.Tip: You can determine the available clock IDs for a target platform using the
platforminfo
utility as described in platforminfo Utility. -
<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
- Applies the defined frequency to the specified CUs and optionally to the specified clock pin on the CU.
For example:
v++ --link --clock.id 1:vadd_1,vadd_3
[clock]
section head using the following format:
[clock]
id=1:vadd_1,vadd_3
--clock.tolerance
--clock.tolerance <arg>
Specifies a clock tolerance as a value, or as a percentage of the
clock frequency. When specifying --clock.freqHz
,
you can also specify the tolerance with either a value or percentage. This updates
the timing constraints to reflect the accepted tolerance. <arg> is specified
as <tolerance>:<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
-
<tolerance>
-
- Can be specified either as a whole number,
indicating the
clock.freqHz
± the specified tolerance value; or as a percentage of the clock frequency specified as a decimal value. -
<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
: Applies the defined clock tolerance to the specified CUs, and optionally to the specified clock pin on the CU.
- Can be specified either as a whole number,
indicating the
-
<cu_0>[.<clk_pin_0>][,<cu_n>[.<clk_pin_n>]]
- Applies the defined clock tolerance to the specified CUs, and optionally to the specified clock pin on the CU.
clock.FreqHz
when this option is not specified.For example:
v++ --link --clock.tolerance 0.10:vadd_1,vadd_3
[clock]
section head using the following format:
[clock]
tolerance=0.10:vadd_1,vadd_3