Add full flash XIP support for ESP32, enabling code and read-only data to
execute/load directly from flash via the MMU cache rather than consuming
precious SRAM. This increases available RAM from ~328KB to effectively
unlimited for code/rodata, while keeping ~121KB for the Go heap.
Changes:
- src/device/esp/esp32.S: Add MMU initialization in call_start_cpu0
- Call ROM bootloader mmu_init() and cache_flash_mmu_set() to map DROM/IROM
- Enable flash cache via ROM Cache_Read_Enable()
- Fix tinygo_scanCurrentStack to spill all register windows for GC
- targets/esp32-interrupts.S: Add exception diagnostics
- targets/esp32.ld: Major linker script restructure for XIP
- Add DROM (4MB @ 0x3F400000) and IROM (4MB @ 0x400D0000) regions
- Move .rodata to DROM, main .text to IROM (both flash-mapped)
- Keep boot code, vectors, and WiFi blob IRAM sections in SRAM0
- Create WiFi arena in SRAM1 pool 7/6 (64KB @ 0x3FFF0000)
- Move .bss and heap to SRAM2 (200KB @ 0x3FFAE000), avoiding ROM/MAC regions
- Add _drom_flash_addr variable (patched by builder with flash offset)
- targets/esp32.json: Add linker wrap flags for malloc/free and WiFi functions
Signed-off-by: deadprogram <ron@hybridgroup.com>
* feat: add inheritable-only field to hide processor-level targets from listing
Processor-level targets like esp32, rp2040, etc. have flash-method set
so they leak through the existing heuristic filter in GetTargetSpecs and
appear in `tinygo targets` output. Add an "inheritable-only" JSON field
that is checked on raw JSON before inheritance resolution, preventing
these non-board targets from being listed while keeping them loadable
for direct builds and inheritance.
Ref: tinygo-org/tinygo#5178
* fix: prevent inheritable-only from propagating to child targets
The InheritableOnly bool field was propagating from parent to child
targets through overrideProperties, which would hide board targets
from GetTargetSpecs. Fix by preserving/restoring the field across
resolveInherits. Also simplify GetTargetSpecs by removing the raw
JSON pre-check workaround and remove nonexistent esp32c6 from tests.
* prevent build commands to use inheritable only targets
The Espressif fork of LLVM now has Xtensa support in the linker LLD.
(This support was written mosly by me). This means we don't have to use
the Espressif GNU toolchain anymore and makes installing TinyGo simpler.
In the future, this also paves the way for ThinLTO support. Right now it
is mostly just a way to simplify TinyGo installation and speed up CI
slightly.
Switch over to LLVM 14 for static builds. Keep using LLVM 13 for regular
builds for now.
This uses a branch of the upstream Espressif branch to fix an issue,
see: https://github.com/espressif/llvm-project/pull/59
This is for consistency with Clang, which always adds a CPU flag even if
it's not specified in CFLAGS.
This commit also adds some tests to make sure the Clang target-cpu
matches the CPU property in the JSON files.
This does have an effect on the generated binaries. The effect is very
small though: on average just 0.2% increase in binary size, apparently
because Cortex-M3 and Cortex-M4 are compiled a bit differently. However,
when rebased on top of https://github.com/tinygo-org/tinygo/pull/2218
(minsize), the difference drops to -0.1% (a slight decrease on average).
This can be very useful for some purposes:
* It makes it possible to disable the UART in cases where it is not
needed or needs to be disabled to conserve power.
* It makes it possible to disable the serial output to reduce code
size, which may be important for some chips. Sometimes, a few kB can
be saved this way.
* It makes it possible to override the default, for example you might
want to use an actual UART to debug the USB-CDC implementation.
It also lowers the dependency on having machine.Serial defined, which is
often not defined when targeting a chip. Eventually, we might want to
make it possible to write `-target=nrf52` or `-target=atmega328p` for
example to target the chip itself with no board specific assumptions.
The defaults don't change. I checked this by running `make smoketest`
before and after and comparing the results.
With this change, it is possible to fully use CGo on ESP32/ESP8266
chips. The following will work:
tinygo flash -target=d1mini -port=/dev/ttyUSB0 ./testdata/cgo/
tinygo flash -target=esp32-mini32 -port=/dev/ttyUSB0 ./testdata/cgo/
Previously it would produce output like the following:
/tmp/tinygo905539688/main.o:(.literal.runtime.run$1$gowrapper+0x150): undefined reference to `strcpy'
/tmp/tinygo905539688/main.o:(.literal.runtime.run$1$gowrapper+0x154): undefined reference to `strlen'
This has been a *lot* of work, trying to understand the Xtensa windowed
registers ABI. But in the end I managed to come up with a very simple
implementation that so far seems to work very well.
I tested this with both blinky examples (with blinky2 slightly edited)
and ./testdata/coroutines.go to verify that it actually works.
Most development happened on the ESP32 QEMU fork from Espressif
(https://github.com/espressif/qemu/wiki) but I also verified that it
works on a real ESP32.
Right now this requires setting the -port parameter, but other than that
it totally works (if esptool.py is installed). It works by converting
the ELF file to the custom ESP32 image format and flashing that using
esptool.py.
This is only very minimal support. More support (such as tinygo flash,
or peripheral access) should be added in later commits, to keep this one
focused.
Importantly, this commit changes the LLVM repo from llvm/llvm-project to
tinygo-org/llvm-project. This provides a little bit of versioning in
case something changes in the Espressif fork. If we want to upgrade to
LLVM 11 it's easy to switch back to llvm/llvm-project until Espressif
has updated their fork.
deadprogram
Carlos Henrique Guardão Gandarez
Ayke van Laethem