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A heap's name is now the list of its tags (dmheap): DMBOOT_DMA_HEAP_TAGS and
DMBOOT_MAIN_HEAP_TAGS name the DMA and the main heap ("dma", "main" by
default). The STM32F746's DMA heap - the DTCM, never cached, no wait states -
is "dma,fast,dtcm": drivers still find it as "dma", and modules asking for
"fast" memory (Dmod_MallocTagged) get it - dmmp3's decoder state took 70 %
of the CPU in the SDRAM, 15 % there.
The STM32F746G Discovery's flash modules get the decoders of carhmi's album
covers (dmimg_jpeg, dmimg_png): loaded by name, not in carhmi's .dmd.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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What
DMBOOT_DMA_HEAP_TAGS/DMBOOT_MAIN_HEAP_TAGSname the DMA and the main heap -"dma","main"by default, as before."dma,fast,dtcm"(configs/mcu/STM32F746xG.cmake,STM32F746ZG.cmake): drivers still find it as"dma"(dmheap_get_context_by_name()matches a tag), and modules asking for fast memory (Dmod_MallocTagged("fast", ...)) get it.dmimg_jpeganddmimg_png: the decoders of carhmi's album covers, which dmimg loads by name (not in carhmi's.dmd).Why
Every module's allocation lands in the SDRAM - the newest default heap - behind a 4 kB data cache. Measured on the board while carhmi-demo plays an MP3 (debugger sampling the PC):
"fast")Before merging - draft
This needs, in this order:
Dmod_MallocTagged) and Heaps tagged by their names, memory of a kind dmheap#22 (tags) merged, and the submoduleslib/dmod,lib/dmheapbumped here. Without the dmheap bump the olddmheap_get_context_by_name("dma")would not find a heap named"dma,fast,dtcm"and the DMA drivers would lose their heap - so not before.Tested on the board with those built locally: the DTCM heap named
dma,fast,dtcm; dmeth, dmsai, dmsdio, dmuart allocate in it as before; dmmp3's state there (memory -m -H fast); the SD card, the audio and the display work. Ethernet: the link is up and frames come in, but DHCP got no address - as all day on this board before this change too (the clock showed--:--), so not checked further.🤖 Generated with Claude Code