Populate the GBA ROM header so that emulators and physical Game Boy
Advance consoles recognize the ROM as a valid game.
Note: The reserve space at the end of the header was hand-tuned. Why
this magic value?
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.
The wasm build tag together with GOARCH=arm was causing problems in the
internal/cpu package. In general, I think having two architecture build
tag will only cause problems (in this case, wasm and arm) so I've
removed the wasm build tag and replaced it with tinygo.wasm.
This is similar to the tinygo.riscv build tag, which is used for older
Go versions that don't yet have RISC-V support in the standard library
(and therefore pretend to be GOARCH=arm instead).
This makes it possible to flash a board even when there are multiple
different kinds of boards attached, e.g. an Arduino Uno and a Circuit
Playground Express. You can find the VID/PID pair in several ways:
1. By running `lsusb` before and after attaching the board and looking
at the new USB device.
2. By grepping for `usb_PID` and `usb_VID` in the TinyGo source code.
3. By checking the Arduino IDE boards.txt from the vendor.
Note that one board may have multiple VID/PID pairs:
* The bootloader and main program may have a different PID, so far
I've seen that the main program generally has the bootloader PID
with 0x8000 added.
* The software running on the board may have an erroneous PID, for
example from a different board. I've seen this happen a few times.
* A single board may have had some revisions which changed the PID.
This is particularly true for the Arduino Uno.
As a fallback, if the given VID/PID pair isn't found, the whole set of
serial ports will be used.
There are many boards which I haven't included yet simply because I
couldn't test them.
Previously it was 1024 bytes, which occasionally ran into a stack
overflow. I hope that 2048 bytes will be enough for most purposes.
I've also removed some 2048-byte stack size settings in JSON files,
which are unnecessary now that the parent (cortex-m.json) sets them.
This only works with a custom bossac build from Arduino, not with the
upstream version. It avoids needing the manual "double tap" to enter
bootloader mode before flashing firmware.
This results in smaller and likely more efficient code. It does require
some architecture specific code for each architecture, but I've kept the
amount of code as small as possible.
Since 2018, Arduino Nanos and clones are sold with a new bootloader, which
requires programming at 115200 baud instead of the 57600 baud required
by the old one.
At the moment, all targets use the Clang compiler to compile C and
assembly files. There is no good reason to make this configurable
anymore and in fact it will make future changes more complicated (and
thus more likely to have bugs). Therefore, I've removed support for
setting the compiler.
Note that the same is not true for the linker. While it makes sense to
standardize on the Clang compiler (because if Clang doesn't support a
target, TinyGo is unlikely to support it either), linkers will remain
configurable for the foreseeable future. One example is Xtensa, which is
supported by the Xtensa LLVM fork but doesn't have support in ld.lld
yet.
I've also fixed a bug in compileAndCacheCFile: it wasn't using the right
CFlags for caching purposes. This could lead to using stale caches. This
commit fixes that too.
This improves compatibility between the regular browser target
(-target=wasm) and the WASI target (-target=wasi). Specifically, it
allows running WASI tests like this:
tinygo test -target=wasi encoding/base32
This currently doesn't work with `tinygo flash` yet (even with
`-programmer=openocd`), you can use pyocd instead. For example, from the
Bluetooth package:
tinygo build -o test.hex -target=microbit-v2-s113v7 ./examples/advertisement/
pyocd flash --target=nrf52 test.hex
I intend to add support for pyocd to work around this issue, so that a simple
`tinygo flash` suffices.
In this commit I've moved all core-specific flags to files for that
specific core. This is a bit of a cleanup (less duplicated JSON) but
should also help in the future when core-specific changes are made, such
as core specific build tags or when the FPU finally gets supported in
TinyGo.
Some notable specific changes:
- I've removed floating point flags from the Teensy 3.6 target. The
reason is that the FPU is not yet supported in TinyGo (in goroutine
stack switching for example) and floating point numbers would only
be supported by C files, not Go files (because the LLVM FPU feature
flags aren't used). This would create an ABI mismatch across CGo.
- I've added the "cpu":"cortex-m7" to the cortex-m7.json file to match
the configuration for the Teensy 4.0. This implies a change to the
nucleo-f722ze (because now it has its CPU field set). Somehow that
reduces the code size, so it looks like a good change.
I don't believe any of these changes should have any practical
consequences.
One issue I've found is in the Cortex-M33 target: it uses armv7m, which
is incorrect: it should be armv8m. But the chip is backwards compatible
so this should mostly work. Switching to armv8m led to a compilation
failure because PRIMASK isn't defined, this may be an actual bug.
The -Qunused-arguments flag disables the warning where some flags are
not relevant to a compilation. This commonly happens when compiling
assembly files (.s or .S files) because some flags are specific to C and
not relevant to assembly.
Because practically all baremetal targets need some form of assembly,
this flag is added to most CFlags. This creates a lot of noise. And it
is also added for compiling C code where it might hide bugs (by hiding
the fact a flag is actually unused).
This commit adds the flag to all assembly compilations and removes them
from all target JSON files.
Previously we used the --export-all linker flag to export most
functions. However, this is not needed and possibly increases binary
size. Instead, we should be exporting the specific functions to be
exported.
This way is more consistent with how picolibc is specified and allows
generating a helpful error message. This error message should never be
generated for TinyGo binary releases, only when doing local development.
This LLVM version breaks CI and is now relatively rather old anyway, so
remove support for it.
This also reverts a workaround for LLVM 9, see a9568932b ("maixbit:
workaround to avoid medium code model").
