[kvm-unit-tests BUG] lib/ldiv32.c breaks arm compilation

[kvm-unit-tests BUG] lib/ldiv32.c breaks arm compilation

[Alexandru Elisei]

Hello,

Commit 0b2d3dafc0d3 ("libcflat: provide long division routines"), which added the
lib/ldiv32.c file, breaks compilation for the arm architecture; arm64 seems to be
working just fine.

On Arch Linux:

$ ./configure --arch=arm --cross-prefix=arm-none-eabi-
$ make clean && make
rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \
      lib/generated/asm-offsets.h
rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \
      arm/.*.d lib/arm/.*.d
  CLEAN (libfdt)
rm -f lib/libfdt/*.o lib/libfdt/.*.d
rm -f lib/libfdt/libfdt.so.1
rm -f lib/libfdt/libfdt.a
rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o
lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o
lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o
lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o
lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o
lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o
lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o
[..]
arm-none-eabi-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access
-std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I
/home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d
-fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body
-Wuninitialized -Wignored-qualifiers -Werror  -fno-omit-frame-pointer 
-fno-stack-protector    -Wno-frame-address -D__U32_LONG_FMT__  -fno-pic  -no-pie 
-Wclobbered  -Wunused-but-set-parameter  -Wmissing-parameter-type 
-Wold-style-declaration -Woverride-init -Wmissing-prototypes -Wstrict-prototypes  
-c -o lib/ldiv32.o lib/ldiv32.c
lib/ldiv32.c: In function '__moddi3':
lib/ldiv32.c:73:11: error: 'rem' may be used uninitialized in this function
[-Werror=maybe-uninitialized]
   73 |  uint64_t rem;
      |           ^~~
lib/ldiv32.c: In function '__umoddi3':
lib/ldiv32.c:75:9: error: 'rem' may be used uninitialized in this function
[-Werror=maybe-uninitialized]
   75 |  return rem;
      |         ^~~
cc1: all warnings being treated as errors
make: *** [<builtin>: lib/ldiv32.o] Error 1
$ arm-none-eabi-gcc --version
arm-none-eabi-gcc (Arch Repository) 10.3.0
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

On Fedora 33:

$ ./configure --arch=arm --cross-prefix=arm-linux-gnu-
$ make clean && make
rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \
      lib/generated/asm-offsets.h
rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \
      arm/.*.d lib/arm/.*.d
  CLEAN (libfdt)
rm -f lib/libfdt/*.o lib/libfdt/.*.d
rm -f lib/libfdt/libfdt.so.1
rm -f lib/libfdt/libfdt.a
rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o
lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o
lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o
lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o
lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o
lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o
lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o
[..]
arm-linux-gnu-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access
-std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I
/home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d
-fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body
-Wuninitialized -Wignored-qualifiers -Werror  -fno-omit-frame-pointer 
-fno-stack-protector    -Wno-frame-address   -fno-pic  -no-pie  -Wclobbered 
-Wunused-but-set-parameter  -Wmissing-parameter-type  -Wold-style-declaration
-Woverride-init -Wmissing-prototypes -Wstrict-prototypes   -c -o lib/ldiv32.o
lib/ldiv32.c
lib/ldiv32.c:1:10: fatal error: inttypes.h: No such file or directory
    1 | #include <inttypes.h>
      |          ^~~~~~~~~~~~
compilation terminated.
make: *** [<builtin>: lib/ldiv32.o] Error 1
$ arm-linux-gnu-gcc --version
arm-linux-gnu-gcc (GCC) 10.2.1 20200826 (Red Hat Cross 10.2.1-3)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Reverting the commit makes arm build again. I am not familiar with toolchains, and
unfortunately I can't propose a fix.

Thanks,

Alex

Re: [kvm-unit-tests BUG] lib/ldiv32.c breaks arm compilation

[Paolo Bonzini]

On 11/05/21 17:43, Alexandru Elisei wrote:
> Hello,
> 
> Commit 0b2d3dafc0d3 ("libcflat: provide long division routines"), which added the
> lib/ldiv32.c file, breaks compilation for the arm architecture; arm64 seems to be
> working just fine.

The Fedora one is fixed in the commit immediately after, which replaces 
inttypes.h with stdint.h.

For Arch Linux I'm not sure what the compiler is complaining about 
(especially since there are no options such as -fno-null-pointer-checks) 
but perhaps we can just initialize rem to 0?  Any chance you can check 
if that affects the assembly output?  (It shouldn't).

Paolo

> On Arch Linux:
> 
> $ ./configure --arch=arm --cross-prefix=arm-none-eabi-
> $ make clean && make
> rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \
>        lib/generated/asm-offsets.h
> rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \
>        arm/.*.d lib/arm/.*.d
>    CLEAN (libfdt)
> rm -f lib/libfdt/*.o lib/libfdt/.*.d
> rm -f lib/libfdt/libfdt.so.1
> rm -f lib/libfdt/libfdt.a
> rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o
> lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o
> lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o
> lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o
> lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o
> lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o
> lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o
> [..]
> arm-none-eabi-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access
> -std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I
> /home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d
> -fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body
> -Wuninitialized -Wignored-qualifiers -Werror  -fno-omit-frame-pointer
> -fno-stack-protector    -Wno-frame-address -D__U32_LONG_FMT__  -fno-pic  -no-pie
> -Wclobbered  -Wunused-but-set-parameter  -Wmissing-parameter-type
> -Wold-style-declaration -Woverride-init -Wmissing-prototypes -Wstrict-prototypes
> -c -o lib/ldiv32.o lib/ldiv32.c
> lib/ldiv32.c: In function '__moddi3':
> lib/ldiv32.c:73:11: error: 'rem' may be used uninitialized in this function
> [-Werror=maybe-uninitialized]
>     73 |  uint64_t rem;
>        |           ^~~
> lib/ldiv32.c: In function '__umoddi3':
> lib/ldiv32.c:75:9: error: 'rem' may be used uninitialized in this function
> [-Werror=maybe-uninitialized]
>     75 |  return rem;
>        |         ^~~
> cc1: all warnings being treated as errors
> make: *** [<builtin>: lib/ldiv32.o] Error 1
> $ arm-none-eabi-gcc --version
> arm-none-eabi-gcc (Arch Repository) 10.3.0
> Copyright (C) 2020 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> 
> On Fedora 33:
> 
> $ ./configure --arch=arm --cross-prefix=arm-linux-gnu-
> $ make clean && make
> rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \
>        lib/generated/asm-offsets.h
> rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \
>        arm/.*.d lib/arm/.*.d
>    CLEAN (libfdt)
> rm -f lib/libfdt/*.o lib/libfdt/.*.d
> rm -f lib/libfdt/libfdt.so.1
> rm -f lib/libfdt/libfdt.a
> rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o
> lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o
> lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o
> lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o
> lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o
> lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o
> lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o
> [..]
> arm-linux-gnu-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access
> -std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I
> /home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d
> -fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body
> -Wuninitialized -Wignored-qualifiers -Werror  -fno-omit-frame-pointer
> -fno-stack-protector    -Wno-frame-address   -fno-pic  -no-pie  -Wclobbered
> -Wunused-but-set-parameter  -Wmissing-parameter-type  -Wold-style-declaration
> -Woverride-init -Wmissing-prototypes -Wstrict-prototypes   -c -o lib/ldiv32.o
> lib/ldiv32.c
> lib/ldiv32.c:1:10: fatal error: inttypes.h: No such file or directory
>      1 | #include <inttypes.h>
>        |          ^~~~~~~~~~~~
> compilation terminated.
> make: *** [<builtin>: lib/ldiv32.o] Error 1
> $ arm-linux-gnu-gcc --version
> arm-linux-gnu-gcc (GCC) 10.2.1 20200826 (Red Hat Cross 10.2.1-3)
> Copyright (C) 2020 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> 
> Reverting the commit makes arm build again. I am not familiar with toolchains, and
> unfortunately I can't propose a fix.
> 
> Thanks,
> 
> Alex
> 

Re: [kvm-unit-tests BUG] lib/ldiv32.c breaks arm compilation

[Alexandru Elisei]

Hi Paolo,

On 5/11/21 5:43 PM, Paolo Bonzini wrote:
> On 11/05/21 17:43, Alexandru Elisei wrote:
>> Hello,
>>
>> Commit 0b2d3dafc0d3 ("libcflat: provide long division routines"), which added the
>> lib/ldiv32.c file, breaks compilation for the arm architecture; arm64 seems to be
>> working just fine.
>
> The Fedora one is fixed in the commit immediately after, which replaces
> inttypes.h with stdint.h.

$ git remote -v show new
* remote new
  Fetch URL: https://gitlab.com/kvm-unit-tests/kvm-unit-tests.git/
  Push  URL: https://gitlab.com/kvm-unit-tests/kvm-unit-tests.git/
  HEAD branch: master
  Remote branches:
    master  tracked
    staging tracked
  Local branch configured for 'git pull':
    master merges with remote master
  Local ref configured for 'git push':
    master pushes to master (up to date)
$ git pull new
Already up to date.
$ git show
commit 0b2d3dafc0d31025636201df923fa0dc8d2e380e (HEAD -> master, new/master)
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Wed May 5 08:33:38 2021 -0400

    libcflat: provide long division routines
[..]

I guess the patch has not been merged yet, right?

>
> For Arch Linux I'm not sure what the compiler is complaining about (especially
> since there are no options such as -fno-null-pointer-checks) but perhaps we can
> just initialize rem to 0?  Any chance you can check if that affects the assembly
> output?  (It shouldn't).

I think it's because I'm using the *arm-none-eabi* toolchain for compilation
instead of arm-linux-gnu, that's the toolchain for cross compiling arm code that
is present in the official Arch Linux repositories. Is that unsupported? I don't
remember any mention of it not being supported, but it's entirely possible that I
just forgot.

With rem initialized to 0 I get this:

rm-none-eabi-ld -nostdlib -Ttext=40010000 -o arm/selftest.elf -T
/home/alex/data/repos/kvm-unit-tests/arm/flat.lds \
    arm/selftest.o arm/cstart.o lib/libcflat.a lib/libfdt/libfdt.a
lib/arm/libeabi.a arm/selftest.aux.o
arm-none-eabi-ld: lib/libcflat.a(printf.o): in function `print_int':
/home/alex/data/repos/kvm-unit-tests/lib/printf.c:72: undefined reference to
`__aeabi_ldivmod'
arm-none-eabi-ld: /home/alex/data/repos/kvm-unit-tests/lib/printf.c:73: undefined
reference to `__aeabi_ldivmod'
arm-none-eabi-ld: lib/libcflat.a(printf.o): in function `print_unsigned':
/home/alex/data/repos/kvm-unit-tests/lib/printf.c:102: undefined reference to
`__aeabi_uldivmod'
arm-none-eabi-ld: lib/libcflat.a(alloc_page.o): in function `_page_alloc_init_area':
/home/alex/data/repos/kvm-unit-tests/lib/alloc_page.c:482: undefined reference to
`__aeabi_uldivmod'
make: *** [/home/alex/data/repos/kvm-unit-tests/arm/Makefile.common:65:
arm/selftest.elf] Error 1

Thanks,

Alex
>
> Paolo
>
>> On Arch Linux:
>>
>> $ ./configure --arch=arm --cross-prefix=arm-none-eabi-
>> $ make clean && make
>> rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \
>>        lib/generated/asm-offsets.h
>> rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \
>>        arm/.*.d lib/arm/.*.d
>>    CLEAN (libfdt)
>> rm -f lib/libfdt/*.o lib/libfdt/.*.d
>> rm -f lib/libfdt/libfdt.so.1
>> rm -f lib/libfdt/libfdt.a
>> rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o
>> lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o
>> lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o
>> lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o
>> lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o
>> lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o
>> lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o
>> [..]
>> arm-none-eabi-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access
>> -std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I
>> /home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d
>> -fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body
>> -Wuninitialized -Wignored-qualifiers -Werror  -fno-omit-frame-pointer
>> -fno-stack-protector    -Wno-frame-address -D__U32_LONG_FMT__  -fno-pic  -no-pie
>> -Wclobbered  -Wunused-but-set-parameter  -Wmissing-parameter-type
>> -Wold-style-declaration -Woverride-init -Wmissing-prototypes -Wstrict-prototypes
>> -c -o lib/ldiv32.o lib/ldiv32.c
>> lib/ldiv32.c: In function '__moddi3':
>> lib/ldiv32.c:73:11: error: 'rem' may be used uninitialized in this function
>> [-Werror=maybe-uninitialized]
>>     73 |  uint64_t rem;
>>        |           ^~~
>> lib/ldiv32.c: In function '__umoddi3':
>> lib/ldiv32.c:75:9: error: 'rem' may be used uninitialized in this function
>> [-Werror=maybe-uninitialized]
>>     75 |  return rem;
>>        |         ^~~
>> cc1: all warnings being treated as errors
>> make: *** [<builtin>: lib/ldiv32.o] Error 1
>> $ arm-none-eabi-gcc --version
>> arm-none-eabi-gcc (Arch Repository) 10.3.0
>> Copyright (C) 2020 Free Software Foundation, Inc.
>> This is free software; see the source for copying conditions.  There is NO
>> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>>
>> On Fedora 33:
>>
>> $ ./configure --arch=arm --cross-prefix=arm-linux-gnu-
>> $ make clean && make
>> rm -f lib/arm/asm-offsets.h lib/arm/asm-offsets.s \
>>        lib/generated/asm-offsets.h
>> rm -f arm/*.{o,flat,elf} lib/arm/libeabi.a lib/arm/eabi_compat.o \
>>        arm/.*.d lib/arm/.*.d
>>    CLEAN (libfdt)
>> rm -f lib/libfdt/*.o lib/libfdt/.*.d
>> rm -f lib/libfdt/libfdt.so.1
>> rm -f lib/libfdt/libfdt.a
>> rm -f lib/.*.d lib/libcflat.a lib/argv.o lib/printf.o lib/string.o lib/abort.o
>> lib/report.o lib/stack.o lib/arm/spinlock.o lib/arm/processor.o lib/arm/stack.o
>> lib/ldiv32.o lib/util.o lib/getchar.o lib/alloc_phys.o lib/alloc_page.o
>> lib/vmalloc.o lib/alloc.o lib/devicetree.o lib/pci.o lib/pci-host-generic.o
>> lib/pci-testdev.o lib/virtio.o lib/virtio-mmio.o lib/chr-testdev.o lib/arm/io.o
>> lib/arm/setup.o lib/arm/mmu.o lib/arm/bitops.o lib/arm/psci.o lib/arm/smp.o
>> lib/arm/delay.o lib/arm/gic.o lib/arm/gic-v2.o lib/arm/gic-v3.o
>> [..]
>> arm-linux-gnu-gcc -marm -mfpu=vfp -mcpu=cortex-a15 -mno-unaligned-access
>> -std=gnu99 -ffreestanding -O2 -I /home/alex/data/repos/kvm-unit-tests/lib -I
>> /home/alex/data/repos/kvm-unit-tests/lib/libfdt -I lib -g -MMD -MF lib/.ldiv32.d
>> -fno-strict-aliasing -fno-common -Wall -Wwrite-strings -Wempty-body
>> -Wuninitialized -Wignored-qualifiers -Werror  -fno-omit-frame-pointer
>> -fno-stack-protector    -Wno-frame-address   -fno-pic  -no-pie  -Wclobbered
>> -Wunused-but-set-parameter  -Wmissing-parameter-type  -Wold-style-declaration
>> -Woverride-init -Wmissing-prototypes -Wstrict-prototypes   -c -o lib/ldiv32.o
>> lib/ldiv32.c
>> lib/ldiv32.c:1:10: fatal error: inttypes.h: No such file or directory
>>      1 | #include <inttypes.h>
>>        |          ^~~~~~~~~~~~
>> compilation terminated.
>> make: *** [<builtin>: lib/ldiv32.o] Error 1
>> $ arm-linux-gnu-gcc --version
>> arm-linux-gnu-gcc (GCC) 10.2.1 20200826 (Red Hat Cross 10.2.1-3)
>> Copyright (C) 2020 Free Software Foundation, Inc.
>> This is free software; see the source for copying conditions.  There is NO
>> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>>
>> Reverting the commit makes arm build again. I am not familiar with toolchains, and
>> unfortunately I can't propose a fix.
>>
>> Thanks,
>>
>> Alex
>>
>

Re: [kvm-unit-tests BUG] lib/ldiv32.c breaks arm compilation

[Paolo Bonzini]

On 11/05/21 19:03, Alexandru Elisei wrote:
>> The Fedora one is fixed in the commit immediately after, which replaces
>> inttypes.h with stdint.h.
> $ git remote -v show new
> * remote new
>    Fetch URL:https://gitlab.com/kvm-unit-tests/kvm-unit-tests.git/
>    Push  URL:https://gitlab.com/kvm-unit-tests/kvm-unit-tests.git/
>    HEAD branch: master
>    Remote branches:
>      master  tracked
>      staging tracked
>    Local branch configured for 'git pull':
>      master merges with remote master
>    Local ref configured for 'git push':
>      master pushes to master (up to date)
> $ git pull new
> Already up to date.
> $ git show
> commit 0b2d3dafc0d31025636201df923fa0dc8d2e380e (HEAD -> master, new/master)
> Author: Paolo Bonzini<pbonzini@redhat.com>
> Date:   Wed May 5 08:33:38 2021 -0400
> 
>      libcflat: provide long division routines
> [..]
> 
> I guess the patch has not been merged yet, right?
> 

Oops, it was only in my own tree.  Pushed now.

Paolo

Re: [kvm-unit-tests BUG] lib/ldiv32.c breaks arm compilation

[Paolo Bonzini]

On 11/05/21 19:03, Alexandru Elisei wrote:
> I think it's because I'm using the*arm-none-eabi*  toolchain for compilation
> instead of arm-linux-gnu, that's the toolchain for cross compiling arm code that
> is present in the official Arch Linux repositories. Is that unsupported? I don't
> remember any mention of it not being supported, but it's entirely possible that I
> just forgot.

No, it's just that there was no difference until now.  If you can add it 
to CI we can make sure it doesn't break.

> With rem initialized to 0 I get this:
> 
> rm-none-eabi-ld -nostdlib -Ttext=40010000 -o arm/selftest.elf -T
> /home/alex/data/repos/kvm-unit-tests/arm/flat.lds \
>      arm/selftest.o arm/cstart.o lib/libcflat.a lib/libfdt/libfdt.a
> lib/arm/libeabi.a arm/selftest.aux.o
> arm-none-eabi-ld: lib/libcflat.a(printf.o): in function `print_int':
> /home/alex/data/repos/kvm-unit-tests/lib/printf.c:72: undefined reference to
> `__aeabi_ldivmod'
> arm-none-eabi-ld: /home/alex/data/repos/kvm-unit-tests/lib/printf.c:73: undefined
> reference to `__aeabi_ldivmod'
> arm-none-eabi-ld: lib/libcflat.a(printf.o): in function `print_unsigned':
> /home/alex/data/repos/kvm-unit-tests/lib/printf.c:102: undefined reference to
> `__aeabi_uldivmod'
> arm-none-eabi-ld: lib/libcflat.a(alloc_page.o): in function `_page_alloc_init_area':
> /home/alex/data/repos/kvm-unit-tests/lib/alloc_page.c:482: undefined reference to
> `__aeabi_uldivmod'
> make: *** [/home/alex/data/repos/kvm-unit-tests/arm/Makefile.common:65:
> arm/selftest.elf] Error 1

So for this we need to include the uldivmod and ldivmod functions 
similar to those in 
https://android.googlesource.com/toolchain/compiler-rt/+/release_32/lib/arm.

The uninitialized warning is because of the division by zero case.  I've 
sent a couple patches to fix everything, please review!

Paolo