DESCRIPTION OF THE COMMAND DB DATABASE.(9)

💖 Description of the Command DB database 💖

okay so this is the Description...DB database.(9) page from the Kernel API Manual, and it is literally all about the Command DB database, bestie. no cap.

Description of the Command DB database. At the start of the command DB memory is the cmd_db_header structure. Think of it as the main character of the header area: the cmd_db_header holds the version, checksum, magic key as well as an array for header for each slave (depicted by the rsc_header). Each h/w based accelerator is a 'slave' (shared resource) and has slave id indicating the type of accelerator. The rsc_header is the header for such individual slaves of a given type. The entries for each of these slaves begin at the rsc_hdr.header_offset. In addition each slave could have auxiliary data that may be needed by the driver. The data for the slave starts at the entry_header.offset to the location pointed to by the rsc_hdr.data_offset. slay, that's the whole memory layout vibe. 🦋

Drivers have a stringified key to a slave/resource. They can query the slave information and get the slave id and the auxiliary data and the length of the data. Using this information, they can format the request to be sent to the h/w accelerator and request a resource state. stringified key in, resource state request out — it's giving useful. 🫶

🌈 SEE ALSO 🌈

• Kernel file ./drivers/soc/qcom/cmd-db.c
• struct entry_header(9)
• struct rsc_hdr(9)
• struct cmd_db_header(9)
• cmd_db_ready(9)
• cmd_db_read_addr(9)
• cmd_db_read_aux_data(9)
• cmd_db_match_resource_addr(9)
• cmd_db_read_slave_id(9)

kisses from the ./drivers/soc/qcom girlies 💅 — October 2026 — Description...DB database.(9) ✨🎀