Problem building bin-arm32-efi/snp.efi with CONSOLE_SERIAL

[msnelling]

I'm trying to build the bin-arm32-efi/snp.efi target for the Raspberry Pi 3 model b+ but am getting the following compilation errors when I have the config option CONSOLE_SERIAL set.

Code:

[VERSION] bin-arm32-efi/version.snp.efi.o
  [LD] bin-arm32-efi/snp.efi.tmp
bin-arm32-efi/blib.a(serial.o): In function `serial_init':
/home/mark/packages/ipxe/src/core/serial.c:145: undefined reference to `uart_select'
bin-arm32-efi/blib.a(serial.o): In function `uart_data_ready':
/home/mark/packages/ipxe/src/include/ipxe/uart.h:112: undefined reference to `uart_read'
/home/mark/packages/ipxe/src/include/ipxe/uart.h:112: undefined reference to `uart_read'
bin-arm32-efi/blib.a(serial.o): In function `uart_receive':
/home/mark/packages/ipxe/src/include/ipxe/uart.h:124: undefined reference to `uart_read'
bin-arm32-efi/blib.a(uart.o): In function `uart_transmit':
/home/mark/packages/ipxe/src/core/uart.c:54: undefined reference to `uart_read'
/home/mark/packages/ipxe/src/core/uart.c:61: undefined reference to `uart_write'
bin-arm32-efi/blib.a(uart.o): In function `uart_flush':
/home/mark/packages/ipxe/src/core/uart.c:75: undefined reference to `uart_read'
/home/mark/packages/ipxe/src/core/uart.c:76: undefined reference to `uart_read'
bin-arm32-efi/blib.a(uart.o): In function `uart_exists':
/home/mark/packages/ipxe/src/core/uart.c:95: undefined reference to `uart_write'
/home/mark/packages/ipxe/src/core/uart.c:96: undefined reference to `uart_read'
/home/mark/packages/ipxe/src/core/uart.c:98: undefined reference to `uart_write'
/home/mark/packages/ipxe/src/core/uart.c:99: undefined reference to `uart_read'
bin-arm32-efi/blib.a(uart.o): In function `uart_init':
/home/mark/packages/ipxe/src/core/uart.c:124: undefined reference to `uart_read'
/home/mark/packages/ipxe/src/core/uart.c:126: undefined reference to `uart_write'
/home/mark/packages/ipxe/src/core/uart.c:131: undefined reference to `uart_write'
/home/mark/packages/ipxe/src/core/uart.c:132: undefined reference to `uart_write'
/home/mark/packages/ipxe/src/core/uart.c:138: undefined reference to `uart_write'
/home/mark/packages/ipxe/src/core/uart.c:141: undefined reference to `uart_write'
bin-arm32-efi/blib.a(uart.o):/home/mark/packages/ipxe/src/core/uart.c:144: more undefined references to `uart_write' follow
bin-arm32-efi/blib.a(uart.o): In function `uart_init':
/home/mark/packages/ipxe/src/core/uart.c:134: undefined reference to `uart_read'
/home/mark/packages/ipxe/src/core/uart.c:135: undefined reference to `uart_read'
arm-linux-gnueabihf-ld: bin-arm32-efi/snp.efi.tmp: hidden symbol `uart_select' isn't defined
arm-linux-gnueabihf-ld: final link failed: Bad value
Makefile.housekeeping:1179: recipe for target 'bin-arm32-efi/snp.efi.tmp' failed
make: *** [bin-arm32-efi/snp.efi.tmp] Error 1
rm bin-arm32-efi/version.snp.efi.o

My toolchain is running on Ubuntu 17.10 x64 with the environment CROSS_COMPILE=arm-linux-gnueabihf- set.

I'm enabling the CONSOLE_SERIAL option in an attempt to get console access to the device over the serial interface. I'm loading the snp.efi module from U-Boot which has the console working correctly.

Has anyone tried something similar or got the serial console working for iPXE on the Raspberry Pi?

[NiKiZe]

Currently the only implementation of UART is in src/arch/x86/include/bits/uart.h "16550-compatible UART"
Meaning there is no implementation of UART for arm, and in turn the reason for this is that there is no outb or inb implemented AFAIK.

I think the U-boot people can help you out a great deal here.