@ubuntu-sru and @ubuntu-sponsors: would you mind doing a new upload of
this package to bionic using the same source as in the last build? This
bug will be solved by rebuilding from the same source using the gcc-arm-
none-eabi package currently in bionic.
Best regards.
** Description changed:
+ [Impact]
+
+ This bug prevents users to produce binaries for some of the targets
+ supported by the compiler. In some case, binaries can get produced but
+ will fail to execute properly.
+
+ To fix this issue the package needs to be rebuilt from the same source.
+ Risk of regressions are thus limited to an issue in the arm-none-eabi
+ toolchain used for the rebuild.
+
+ The bug stems from newlib having libraries for various targets (called
+ multilib) in a different location than where the compiler expects them
+ to be, thus making the wrong libraries get selected. The location of the
+ newlib libraries is decided at build time by asking the compiler
+ (provided in gcc-arm-none-eabi) where it will be looking for these.
+ Unfortunately, the version of newlib in Ubuntu bionic was built using a
+ different version of gcc-arm-none-eabi than the one currently in bionic
+ and GCC changed where to look for library between those 2 versions. This
+ is why rebuilding against the current gcc-arm-none-eabi will solve the
+ issue.
+
+ [Test Case]
+
+ Compile the following hello world testcase (in hello.c) with arm-none-
+ eabi-gcc -o hello.axf hello.c -mthumb -Wl,--gc-sections -ffast-math
+ -march=armv7e-m -specs=rdimon.specs
+
+ #include <stdio.h>
+
+ int
+ main (void)
+ {
+ puts ("Hello, World!");
+ return 0;
+ }
+
+ [Regression Potential]
+
+ As explained in the impact, no source change is necessary so any
+ regression would be due to bugs in the compiler which would be good to
+ catch anyway.
+
+
+ Original bug report below:
+
The multilib setup is not working in the bionic version of gcc-arm-none-
eabi (gcc v6.3.1). For example, if I build a project with
"-mcpu=cortex-m4" or "-march=armv7e-m" and link with:
arm-none-eabi-gcc -o someoutput.elf object1.o object2.o -mthumb -Wl
,--gc-sections -ffast-math -march=armv7-m -Tlinker_script.ld
I get as output:
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/bin/ld: error:
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/lib/crt0.o: Conflicting
CPU architectures 13/1
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/bin/ld: failed to
merge target specific data of file
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/lib/crt0.o
arm-none-eabi-readelf -A on any of my object files produces:
Attribute Section: aeabi
File Attributes
- Tag_CPU_name: "Cortex-M4"
- Tag_CPU_arch: v7E-M
- Tag_CPU_arch_profile: Microcontroller
- Tag_THUMB_ISA_use: Thumb-2
- Tag_ABI_PCS_wchar_t: 4
- Tag_ABI_FP_number_model: Finite
- Tag_ABI_align_needed: 8-byte
- Tag_ABI_align_preserved: 8-byte, except leaf SP
- Tag_ABI_enum_size: small
- Tag_ABI_optimization_goals: Prefer Speed
- Tag_CPU_unaligned_access: v6
+ Tag_CPU_name: "Cortex-M4"
+ Tag_CPU_arch: v7E-M
+ Tag_CPU_arch_profile: Microcontroller
+ Tag_THUMB_ISA_use: Thumb-2
+ Tag_ABI_PCS_wchar_t: 4
+ Tag_ABI_FP_number_model: Finite
+ Tag_ABI_align_needed: 8-byte
+ Tag_ABI_align_preserved: 8-byte, except leaf SP
+ Tag_ABI_enum_size: small
+ Tag_ABI_optimization_goals: Prefer Speed
+ Tag_CPU_unaligned_access: v6
But "arm-none-eabi-readelf -A /usr/lib/gcc/arm-none-eabi/6.3.1
/../../../arm-none-eabi/lib/crt0.o" gives
Attribute Section: aeabi
File Attributes
- Tag_CPU_arch: v4
- Tag_ARM_ISA_use: Yes
+ Tag_CPU_arch: v4
+ Tag_ARM_ISA_use: Yes
If I define "void _init(void){}" and use -nostartfiles, compilation
finishes but the resulting binary does not work. I have not examined the
output file but it appears that it has somehow linked to code containing
ARM as well as thumb code:
# readelf -A someoutput.elf
Attribute Section: aeabi
File Attributes
- Tag_CPU_name: "Cortex-M4"
- Tag_CPU_arch: v7E-M
- Tag_CPU_arch_profile: Microcontroller
- Tag_ARM_ISA_use: Yes
- Tag_THUMB_ISA_use: Thumb-2
- Tag_ABI_PCS_wchar_t: 4
- Tag_ABI_FP_denormal: Needed
- Tag_ABI_FP_exceptions: Needed
- Tag_ABI_FP_number_model: IEEE 754
- Tag_ABI_align_needed: 8-byte
- Tag_ABI_align_preserved: 8-byte, except leaf SP
- Tag_ABI_enum_size: small
- Tag_ABI_optimization_goals: Prefer Speed
- Tag_CPU_unaligned_access: v6
+ Tag_CPU_name: "Cortex-M4"
+ Tag_CPU_arch: v7E-M
+ Tag_CPU_arch_profile: Microcontroller
+ Tag_ARM_ISA_use: Yes
+ Tag_THUMB_ISA_use: Thumb-2
+ Tag_ABI_PCS_wchar_t: 4
+ Tag_ABI_FP_denormal: Needed
+ Tag_ABI_FP_exceptions: Needed
+ Tag_ABI_FP_number_model: IEEE 754
+ Tag_ABI_align_needed: 8-byte
+ Tag_ABI_align_preserved: 8-byte, except leaf SP
+ Tag_ABI_enum_size: small
+ Tag_ABI_optimization_goals: Prefer Speed
+ Tag_CPU_unaligned_access: v6
I can work around the problem by manually specifying compatible versions
of libc and libgcc with -nostdlib:
-nostdlib /usr/lib/arm-none-eabi/newlib/thumb/libc.a /usr/lib/gcc/arm-
none-eabi/6.3.1/thumb/v7e-m/libgcc.a
This produces a working binary. However, there is still something wrong
because readelf -A still includes "Tag_ARM_ISA_use: Yes":
Attribute Section: aeabi
File Attributes
- Tag_CPU_name: "Cortex-M4"
- Tag_CPU_arch: v7E-M
- Tag_CPU_arch_profile: Microcontroller
- Tag_ARM_ISA_use: Yes
- Tag_THUMB_ISA_use: Thumb-2
- Tag_ABI_PCS_wchar_t: 4
- Tag_ABI_FP_denormal: Needed
- Tag_ABI_FP_exceptions: Needed
- Tag_ABI_FP_number_model: IEEE 754
- Tag_ABI_align_needed: 8-byte
- Tag_ABI_align_preserved: 8-byte, except leaf SP
- Tag_ABI_enum_size: small
- Tag_ABI_optimization_goals: Prefer Speed
- Tag_CPU_unaligned_access: v6
+ Tag_CPU_name: "Cortex-M4"
+ Tag_CPU_arch: v7E-M
+ Tag_CPU_arch_profile: Microcontroller
+ Tag_ARM_ISA_use: Yes
+ Tag_THUMB_ISA_use: Thumb-2
+ Tag_ABI_PCS_wchar_t: 4
+ Tag_ABI_FP_denormal: Needed
+ Tag_ABI_FP_exceptions: Needed
+ Tag_ABI_FP_number_model: IEEE 754
+ Tag_ABI_align_needed: 8-byte
+ Tag_ABI_align_preserved: 8-byte, except leaf SP
+ Tag_ABI_enum_size: small
+ Tag_ABI_optimization_goals: Prefer Speed
+ Tag_CPU_unaligned_access: v6
Previously, using xenial and gcc v4, readelf gives the following output on
the output binary:
Attribute Section: aeabi
File Attributes
- Tag_CPU_name: "7E-M"
- Tag_CPU_arch: v7E-M
- Tag_CPU_arch_profile: Microcontroller
- Tag_THUMB_ISA_use: Thumb-2
- Tag_ABI_PCS_wchar_t: 4
- Tag_ABI_FP_denormal: Needed
- Tag_ABI_FP_exceptions: Needed
- Tag_ABI_FP_number_model: IEEE 754
- Tag_ABI_align_needed: 8-byte
- Tag_ABI_enum_size: small
- Tag_ABI_optimization_goals: Prefer Speed
- Tag_CPU_unaligned_access: v6
+ Tag_CPU_name: "7E-M"
+ Tag_CPU_arch: v7E-M
+ Tag_CPU_arch_profile: Microcontroller
+ Tag_THUMB_ISA_use: Thumb-2
+ Tag_ABI_PCS_wchar_t: 4
+ Tag_ABI_FP_denormal: Needed
+ Tag_ABI_FP_exceptions: Needed
+ Tag_ABI_FP_number_model: IEEE 754
+ Tag_ABI_align_needed: 8-byte
+ Tag_ABI_enum_size: small
+ Tag_ABI_optimization_goals: Prefer Speed
+ Tag_CPU_unaligned_access: v6
(Also, what happened to gdb-arm-none-eabi?)
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https://bugs.launchpad.net/bugs/1767223
Title:
multilib selects wrong start files
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