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Ayke van Laethem
907d90105a
Instead of always starting a new goroutine for the main goroutine, run
the main goroutine on the system stack.
The system stack is not occupied with scheduling, instead each goroutine
that wants to pause itself calls into the scheduler which will switch to
the next task (goroutine) to run, or sleeps.
There are various advantages of this over the previous system:
* When the program doesn't start a goroutine, the code size and RAM
consumption is close to what you'd get with `-scheduler=none`.
* When the program does start a goroutine, there is still a reduction
in RAM consumption because only one extra stack is needed.
* Because tasks directly switch to the next task to run, only a single
task switch is needed instead of two (goroutine -> scheduler ->
goroutine). This should improve task switching performance.
I kept the current behavior for WebAssembly/Asyncify. I looked into how
the same benefits can be realized for WebAssembly but couldn't easily
find how to do that. Maybe this can be done separately, or maybe we'll
just wait for the stack switching proposal to finish.
The code for Cortex-M is currently more complicated than I'd like, and
therefore can sometimes result in a slight increase in code size. I'd
like to fix this eventually but am still looking into good ways to do
this. I still think this change is generally beneficial because many
programs see big reductions in code size when compiling for Cortex-M.
115 lines
2.8 KiB
Plaintext
115 lines
2.8 KiB
Plaintext
/* Linker script for the ESP8266 */
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MEMORY
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{
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/* Data RAM. Allows byte access. */
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DRAM (rw) : ORIGIN = 0x3FFE8000, LENGTH = 80K
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/* Instruction RAM. */
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IRAM (x) : ORIGIN = 0x40100000, LENGTH = 32K
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}
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/* The entry point. It is set in the image flashed to the chip, so must be
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* defined.
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*/
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ENTRY(main)
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SECTIONS
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{
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/* Mutable global variables.
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*/
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.data : ALIGN(4)
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{
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_sdata = ABSOLUTE(.);
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*(.data)
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*(.data.*)
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} >DRAM
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/* Constant global variables.
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* Note that they still need to be loaded in RAM because the ESP8266 doesn't
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* allow byte access to flash.
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*/
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.rodata : ALIGN(4)
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{
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*(.rodata)
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*(.rodata.*)
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} >DRAM
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/* Global variables that are mutable and zero-initialized.
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*/
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.bss (NOLOAD) : ALIGN(4)
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{
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. = ALIGN (4);
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_sbss = ABSOLUTE(.);
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*(.bss)
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*(.bss.*)
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. = ALIGN (4);
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_ebss = ABSOLUTE(.);
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} >DRAM
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/* Constant literals and code. Loaded into IRAM for now. Eventually, most
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* code should be executed directly from flash.
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* Note that literals must be before code for the l32r instruction to work.
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*/
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.text : ALIGN(4)
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{
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*(.literal .text)
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*(.literal.* .text.*)
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} >IRAM
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}
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_globals_start = _sdata;
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_globals_end = _ebss;
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_heap_start = _ebss;
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_heap_end = ORIGIN(DRAM) + LENGTH(DRAM);
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/* It appears that the stack is set to 0x3ffffff0 when main is called.
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* Be conservative and scan all the way up to the end of the RAM.
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*/
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_stack_top = 0x40000000;
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/* This is the stack bottom according to this forum post:
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* https://bbs.espressif.com/viewtopic.php?t=8879#p19038
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*/
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_stack_bottom = 0x3fffeb2c;
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/* Functions normally provided by a libc.
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* Source:
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* https://github.com/espressif/ESP8266_NONOS_SDK/blob/master/ld/eagle.rom.addr.v6.ld
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*/
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memcpy = 0x4000df48;
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memmove = 0x4000e04c;
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memset = 0x4000e190;
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/* Compiler runtime functions provided by the ROM.
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* Source:
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* https://github.com/espressif/ESP8266_NONOS_SDK/blob/master/ld/eagle.rom.addr.v6.ld
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*/
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__adddf3 = 0x4000c538;
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__addsf3 = 0x4000c180;
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__divdf3 = 0x4000cb94;
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__divdi3 = 0x4000ce60;
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__divsi3 = 0x4000dc88;
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__extendsfdf2 = 0x4000cdfc;
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__fixdfsi = 0x4000ccb8;
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__fixunsdfsi = 0x4000cd00;
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__fixunssfsi = 0x4000c4c4;
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__floatsidf = 0x4000e2f0;
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__floatsisf = 0x4000e2ac;
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__floatunsidf = 0x4000e2e8;
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__floatunsisf = 0x4000e2a4;
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__muldf3 = 0x4000c8f0;
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__muldi3 = 0x40000650;
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__mulsf3 = 0x4000c3dc;
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__subdf3 = 0x4000c688;
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__subsf3 = 0x4000c268;
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__truncdfsf2 = 0x4000cd5c;
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__udivdi3 = 0x4000d310;
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__udivsi3 = 0x4000e21c;
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__umoddi3 = 0x4000d770;
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__umodsi3 = 0x4000e268;
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__umulsidi3 = 0x4000dcf0;
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/* Proprietary ROM function needed for proper clock configuration.
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*/
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rom_i2c_writeReg = 0x400072d8;
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