address1, 4 bytes overlay data
address2, 4 bytes overlay data
etc
The data is overlayed over the specified addresses, in runtime. On some chips its 8 bytes instead of 4. On a typical Broadcom/Cypress chip you have 128 or 256 entries.
By the time the chip is 2-3 years in the market and still getting firmware updates, ~98% of them are used by existing firmware, so there are only 5-10 free entries by the time the chip is considered "obsolete".
Case in point: the Broadcom/Cypress BCM43455 chip on the raspberry pi is almost out of patch entries. Broadcom have switched to their usual tactic of stalling for years on known, reproducible bug reports.
By the time the chip is 2-3 years in the market and still getting firmware updates, ~98% of them are used by existing firmware, so there are only 5-10 free entries by the time the chip is considered "obsolete".
Case in point: the Broadcom/Cypress BCM43455 chip on the raspberry pi is almost out of patch entries. Broadcom have switched to their usual tactic of stalling for years on known, reproducible bug reports.