add support for Cortex-R devices

[japaric]

r? @alexcrichton
cc @paoloteti

[japaric]

@alexcrichton could you publish a new release after this is merged? We need one to build rust-std components for the Cortex-R targets.

[japaric]

cc @kenkeiter

[paoloteti]

Is this correct? eb = big-endian in armeb . I use 'armeb-eabi' and not arm-none-eabi in this case (Linaro toolchain)

[japaric]

The arm-none-eabi-gcc toolchain can also generate big endian code but it needs the -mbig-endian flag. The latest commit addresses that.

$ arm-none-eabi-readelf -h ./target/armebv7r-none-eabihf/debug/build/foo-728ce1e8d146ec12/out/libfoo.a

File: ./target/armebv7r-none-eabihf/debug/build/foo-728ce1e8d146ec12/out/libfoo.a(foo.o)
ELF Header:
  Magic:   7f 45 4c 46 01 02 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF32
  Data:                              2's complement, big endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           ARM
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          1188 (bytes into file)
  Flags:                             0x5000000, Version5 EABI
  Size of this header:               52 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           40 (bytes)
  Number of section headers:         22
  Section header string table index: 21

$ arm-none-eabi-readelf -h ./target/armv7r-none-eabi/debug/build/foo-728ce1e8d146ec12/out/libfoo.a

File: ./target/armv7r-none-eabi/debug/build/foo-728ce1e8d146ec12/out/libfoo.a(foo.o)
ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           ARM
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          1168 (bytes into file)
  Flags:                             0x5000000, Version5 EABI
  Size of this header:               52 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           40 (bytes)
  Number of section headers:         22
  Section header string table index: 21

[alexcrichton]

👍

[japaric]

@alexcrichton Thanks!