From eedc9f98608a0f43278658a855e494f9390a9c3c Mon Sep 17 00:00:00 2001 From: Phil Howard Date: Fri, 5 Aug 2022 09:43:22 +0100 Subject: [PATCH] ports/rp2: Mark gc_heap NOLOAD for faster boot. Create a new linker section .unitialized_bss for bss that does not need zero-initialising. Move gc_heap to .unitialized_bss section. Saves ~30ms from rising edge of RESET to setting a pin HIGH in MicroPython. Zero fill happens in Pico SDK crt0.S before ROSC is configured. It's very, very slow. Signed-off-by: Phil Howard --- ports/rp2/main.c | 2 +- ports/rp2/memmap_mp.ld | 6 ++++++ 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/ports/rp2/main.c b/ports/rp2/main.c index d976464de1cc5..1062236a3916b 100644 --- a/ports/rp2/main.c +++ b/ports/rp2/main.c @@ -66,7 +66,7 @@ #endif extern uint8_t __StackTop, __StackBottom; -static char gc_heap[MICROPY_GC_HEAP_SIZE]; +__attribute__((section(".uninitialized_bss"))) static char gc_heap[MICROPY_GC_HEAP_SIZE]; // Embed version info in the binary in machine readable form bi_decl(bi_program_version_string(MICROPY_GIT_TAG)); diff --git a/ports/rp2/memmap_mp.ld b/ports/rp2/memmap_mp.ld index 0dc96743ea5cb..82f9cb01c3eff 100644 --- a/ports/rp2/memmap_mp.ld +++ b/ports/rp2/memmap_mp.ld @@ -180,6 +180,12 @@ SECTIONS *(.uninitialized_data*) } > RAM + /* bss without zero init on startup */ + .uninitialized_bss (NOLOAD): { + . = ALIGN(4); + *(.uninitialized_bss*) + } > RAM + /* Start and end symbols must be word-aligned */ .scratch_x : { __scratch_x_start__ = .; pFad - Phonifier reborn

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