DCache: Add __dcacheline_aligned & __dcacheline_unique tokens #98578
+125 −36
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JarmouniA force-pushed the dev_dcache_aligned_unique branch from 8fc403a to 209a631 Compare 
maass-hamburg requested changes Oct 31, 2025
Comment on lines +155 to +163
| #if defined(CONFIG_DCACHE_LINE_SIZE) | ||
| SECTION_DATA_PROLOGUE(data_cache,,SUBALIGN(CONFIG_DCACHE_LINE_SIZE)) | ||
| { | ||
| PLACE_SYMBOL_HERE(__data_cache_start); | ||
| KEEP(*(SORT_BY_NAME(".data_cache*"))) | ||
| . = ALIGN(CONFIG_DCACHE_LINE_SIZE); | ||
| PLACE_SYMBOL_HERE(__data_cache_end); | ||
| } GROUP_DATA_LINK_IN(RAMABLE_REGION, RAMABLE_REGION) | ||
| #endif /* CONFIG_DCACHE_LINE_SIZE */ |
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I don't like that this automatically means, that all variables with this attribute land in the data section. That means that variables, are initialized with zero, will no longer land in the bss section. That leads to increase in size in flash, as they now can't be optimized out.
Add __dcacheline_aligned which ensures data cache line alignment. Add __dcacheline_unique which puts a static variable in a section that contains only data cache line aligned variables. This results in variables being aligned and in a unique data cache line each. Co-authored-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no> Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no> Signed-off-by: Abderrahmane JARMOUNI <git@jarmouni.me>
Add test which checks that variable tagged with __dcacheline_aligned is correctly aligned, and that the variables tagged with __dcacheline_unique are in the proper section that gives a unique data cache line for each. Co-authored-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no> Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no> Signed-off-by: Abderrahmane JARMOUNI <git@jarmouni.me>
Replace __aligned(CONFIG_DCACHE_LINE_SIZE) with __dcacheline_aligned across Zephyr Signed-off-by: Abderrahmane JARMOUNI <git@jarmouni.me>
JarmouniA force-pushed the dev_dcache_aligned_unique branch from be55f5d to f42111b Compare 
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New version of #95888
Add
__dcacheline_alignedmacro which ensures data cache line alignment for variables.Add
__dcacheline_uniquemacro which puts a static variable in a linker section that contains only data cache line aligned variables. This results in those variables being aligned and in a unique data cache line each.Usage:
static uint8_t var1 __dcacheline_aligned;static uint8_t var2 __dcacheline_unique;