87 lines
3.0 KiB
Plaintext
87 lines
3.0 KiB
Plaintext
The RH DPDK Configuration System
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================================
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Overview
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--------
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As we're aware, the DPDK configuration is an important thing to manage
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well. We have a number of concerns that must be addressed in any
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configuration management system.
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1. We want to make sure that we have 'conscious' configurations made up
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for each platform, and for each DPDK-enabled package
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2. We want to make sure that when DPDK project adds a new configuration,
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we make a conscious decision about whether we enable that
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configuration.
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3. We need to make sure that we can accommodate the wacky new
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configuration management system coming down the pipe for
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DPDK (meson+ninja).
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Procedure (High level)
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----------------------
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Taking some inspiration from the kernel config DPDK packages will use
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the following procedure:
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1. We generate the DPDK configuration from source (as we do today with
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'make T=TEMPLATE config'). This creates a base configuration file.
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In this case TEMPLATE is the combination of $arch and $release that
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can vary for the package.
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2. We generate a sha256 sum from that file (based on a rules engine
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described later).
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3. We take a hand-built checked-in configuration (dpdk.TEMPLATE.config)
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which has a special tag inside containing the required base sha256
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sum and compare with the generated sha256 sum.
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4. If the comparison succeeds, we overwrite the generated config with
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the hand-built config. Proceed building as normal.
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5. If the comparison fails, we halt the build. Clearly a new
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configuration was introduced which was not considered and needs to be
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addressed.
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It's important to note that if the default configuration changes, that
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will also cause the shasum to change. Even if the default for a
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parameter that we override changes, this will trip up this simplistic
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version.
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SHA Sum
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-------
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To generate the sha256 sum:
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* remove all 'comment' and empty lines
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* sort the remaining lines
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* calculate the sha sum
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This is expressed in bash as a one-liner:
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egrep -v ^"$cmnt" $1 | egrep -v ^$ | sort -u | sha256sum | cut -d" " -f1
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The new DPDK configuration will be generating into a header file
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(rte_config.h), and so some 'forward' consideration was given to making
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the comment line as configurable (instead of using straight '#') - hence the
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'$cmnt' variable.
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The SHA sum will be identified in the 'new' header by the standard ascii
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tag format:
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# -*- cfg-sha: [a-z0-9]+
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Or in the case of a .c file:
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/* -*- cfg-sha: [a-z0-9]+ */
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Helper scripts
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--------------
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Included are a set of scripts for DPDK configuration, which replaces
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the original setconf functions in the old spec file.
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* set_config.sh - A script which copies the new DPDK configuration over the
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old one. This validates the sha sum.
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* gen_config_group.sh - A script which reads the .spec file for all of the
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architectures and generates starting configurations.
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Use this script to get a baseline configuration for
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modifying.
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* configlib.sh - A library for generating and reading SHA sums.
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