67 lines
3.2 KiB
Markdown
67 lines
3.2 KiB
Markdown
# Example Project for GCC ARM
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This example is for Cortex M series, but can be adopted for other architectures.
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## Design
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* All library options are defined in `Header/user_settings.h`.
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* The memory map is located in the linker file in `linker.ld`.
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* Entry point function is `reset_handler` in `armtarget.c`.
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* The RTC and RNG hardware interface needs implemented for real production applications in `armtarget.c`
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## Building
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1. Make sure you have `gcc-arm-none-eabi` installed.
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2. Modify the `Makefile.common`:
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* Use correct toolchain path `TOOLCHAIN`.
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* Use correct architecture 'ARCHFLAGS' (default is cortex-m0 / thumb). See [GCC ARM Options](https://gcc.gnu.org/onlinedocs/gcc-4.7.3/gcc/ARM-Options.html) `-mcpu=name`.
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3. Use `make` and it will build the static library and wolfCrypt test/benchmark and wolfSSL TLS client targets as `.elf` and `.hex` in `/Build`.
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### Building for Raspberry Pi
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Example `Makefile.common` changes for Rasperry Pi with Cortex-A53:
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1. Change ARCHFLAGS to `ARCHFLAGS = -mcpu=cortex-a53 -mthumb -mabi=aapcs` to specify Cortex-A53.
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2. Comment out `SRC_LD`, since custom memory map is not applicable.
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3. Clear `TOOLCHAIN`, so it will use default `gcc`. Set `TOOLCHAIN = `
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4. Comment out `LDFLAGS += --specs=nano.specs --specs=nosys.specs` to disable newlib-nano.
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Note: To comment out a line in a Makefile use place `#` in front of line.
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### Example Build
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```
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make clean && make
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text data bss dec hex filename
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50076 2508 44 52628 cd94 ./Build/WolfCryptTest.elf
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text data bss dec hex filename
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39155 2508 60 41723 a2fb ./Build/WolfCryptBench.elf
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text data bss dec hex filename
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70368 464 36 70868 114d4 ./Build/WolfSSLClient.elf
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```
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## Performace Tuning Options
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These settings are located in `Header/user_settings.h`.
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* `DEBUG_WOLFSSL`: Undefine this to disable debug logging.
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* `NO_ERROR_STRINGS`: Disables error strings to save code space.
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* `NO_INLINE`: Disabling inline function saves about 1KB, but is slower.
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* `WOLFSSL_SMALL_STACK`: Enables stack reduction techniques to allocate stack sections over 100 bytes from heap.
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* `USE_FAST_MATH`: Uses stack based math, which is faster than the heap based math.
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* `ALT_ECC_SIZE`: If using fast math and RSA/DH you can define this to reduce your ECC memory consumption.
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* `FP_MAX_BITS`: Is the maximum math size (key size * 2). Used only with `USE_FAST_MATH`.
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* `ECC_TIMING_RESISTANT`: Enables timing resistance for ECC and uses slightly less memory.
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* `ECC_SHAMIR`: Doubles heap usage, but slightly faster
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* `RSA_LOW_MEM`: Half as much memory but twice as slow. Uses Non-CRT method for private key.
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AES GCM: `GCM_SMALL`, `GCM_WORD32` or `GCM_TABLE`: Tunes performance and flash/memory usage.
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* `CURVED25519_SMALL`: Enables small versions of Ed/Curve (FE/GE math).
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* `USE_SLOW_SHA`: Enables smaller/slower version of SHA.
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* `USE_SLOW_SHA256`: About 2k smaller and about 25% slower
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* `USE_SLOW_SHA512`: Over twice as small, but 50% slower
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* `USE_CERT_BUFFERS_1024` or `USE_CERT_BUFFERS_2048`: Size of RSA certs / keys to test with.
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* `BENCH_EMBEDDED`: Define this if using the wolfCrypt test/benchmark and using a low memory target.
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