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insane-adding-machines / frosted

Frosted: Free POSIX OS for tiny embedded devices
GNU General Public License v2.0
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Can't compile with arm-frosted-eabi-gcc for a cortex M7 #114

Closed nathanLoretan closed 7 years ago

nathanLoretan commented 7 years ago

Hello, perhaps it's my bad but always when I try to compile for a cortex M7, I want to use a board stm32f746-discovery, I have this error: Assembler messages: Error: unknown cpu `cortex-m7' Error: unrecognized option -mcpu=cortex-m7 make[1]: [init.o] Error 1 make: [binutils] Error 2

When I compile for cortex M4 or M3 I have no problem it's only for cortex M7.

danielinux commented 7 years ago

Currently we don't have multi-arch support for our compiler. You can safely compile for your M7 target using cortex-m3 flags. @maximevince is working on a multi-arch setup for the compiler.

Can you describe what you are trying to do? Are you compiling an application or a library for frosted? Any specific reason why you'd need M7 optimizations?

danielinux commented 7 years ago

FYI: This is the suggested set of flags to compile userspace apps and libraries for frosted:

CFLAGS: -mthumb -mlittle-endian -mthumb-interwork -ffunction-sections -mcpu=cortex-m3 -DCORE_M3 -D__frosted__ -nostartfiles -fPIC -mlong-calls -fno-common -msingle-pic-base -mno-pic-data-is-text-relative -Wstack-usage=1024

LDFLAGS: -fPIC -mlong-calls -fno-common -Wl,-elf2flt -lgloss

nathanLoretan commented 7 years ago

I try to make a port for using ugfx library and frosted. to do this, I need to compile the ugfx library with specifying cortex-m7. And for compile the library I use arm-frosted-eabi-gcc. It will work if I compile the library ugfx with arm-none-eabi-gcc and the kernel frosted with arm-frosted-eabi-gcc?

danielinux commented 7 years ago

Any specific reason to compile with -mcpu=cortex-m7? Why can't you compile with -m3?

nathanLoretan commented 7 years ago

I will try to compile with -m3. cortex-m7 is the automatically specifying when you choose the board stm32f746-discovery on the library ugfx.

danielinux commented 7 years ago

@nathanLoretan be careful, because you are not compiling a standalone, baremetal application, but rather a unix userspace app, which should be by definition generic (except maybe for the resolution of the screen).

You should not need anything that is board specific, all you need is accessing /dev/fb0 which is a generic (memory mapped) device, using standard system calls (open/lseek/write).

Please have a look on how we are doing it in Id software's DOOM port: https://github.com/insane-adding-machines/DOOM/blob/master/frosted-doom/i_video_fbdev.c#L363