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Clarify corner case behavior of --device option #2779

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Merged
merged 5 commits into from
Oct 18, 2024
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Clarify corner case behavior of --device option #2779

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01ddb1b
Clarify corner case behavior of --device option
petergrossmann21 Oct 17, 2024
307f0c8
Merge branch 'master' into update_device_option_documentation
AlexandreSinger Oct 17, 2024
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Incorporate PR feedback
petergrossmann21 Oct 18, 2024
4332584
Merge branch 'master' into update_device_option_documentation
petergrossmann21 Oct 18, 2024
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Merge branch 'update_device_option_documentation' of https://github.c…
petergrossmann21 Oct 18, 2024
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15 changes: 11 additions & 4 deletions doc/src/vpr/command_line_usage.rst
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Expand Up @@ -200,12 +200,19 @@ General Options

.. option:: --device <string>

Specifies which device layout/floorplan to use from the architecture file.
Specifies which device layout/floorplan to use from the architecture file. Valid values are:

``auto`` uses the smallest device satisfying the circuit's resource requirements.
Other values are assumed to be the names of device layouts defined in the :ref:`arch_grid_layout` section of the architecture file.
* ``auto`` VPR uses the smallest device satisfying the circuit's resource requirements, with device layout specified using the ``auto_layout`` section of the architecture file.
* Any string matching ``name`` attribute of a device layout defined with a ``fixed_layout`` tag in the :ref:`arch_grid_layout` section of the architecture file.

.. note:: If the architecture contains both ``<auto_layout>`` and ``<fixed_layout>`` specifications, specifying an ``auto`` device will use the ``<auto_layout>``.
If the value specified is neither ``auto`` nor matches the ``name`` attribute value of a ``<fixed_layout>`` tag, VPR issues an error.

In the event that no ``<auto_layout>`` tag is present in the architecture file, this option has the following behaviour:
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@vaughnbetz vaughnbetz Oct 17, 2024

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I would delete thse 3 lines as now they are covered by the introduction of --auto above.

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@petergrossmann21 petergrossmann21 Oct 18, 2024

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@vaughnbetz I kept the line documenting how VPR does error handling here, but deleted the bullet points below the highlights; I believe this better captures the desired elimination of redundancy. Let me know if additional changes are desired.


* ``auto`` VPR uses the smallest device amongst all ``fixed_layout`` specifications into which the design can be packed.
* Otherwise, the value of the ``fixed_layout`` attribute ``name`` is matched as when an ``<auto_layout>`` tag is present.

.. note:: If the only layout in the architecture file is a single device specified using ``<fixed_layout>``, it is recommended to always specify the ``--device`` option; this prevents the value ``--device auto`` from interfering with operations supported only for ``<fixed_layout>`` grids.

**Default:** ``auto``

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