hosts all source download tar
files for each release at https://www.xilinx.com/support/download/index.html/content/xilinx/en/downloadNav/embedded-design-tools.html.
By default, PetaLinux points to pre-mirrors using
If any component is rebuilt from scratch, BitBake or devtool searches for its source in pre-mirrors and downloads the mirror URL. Later, it searches in SRC_URI of recipes for downloading the source of that component. If you configure any value through petalinux.xilinx.com, and finally in the SRC_URI in recipes., it will first search in the configured pre-mirrors, then on
You can add more mirrors by adding
SOURCE_MIRROR_URL += file:///home/you/your-download-dir/ in <plnx-proj-root>/project-spec/meta-user/conf/petalinuxbsp.conf.
For more information on how to set SSTATE and DL_DIR, see How to Reduce Build Time using SSTATE Cache.