Re: [UNIKRAFT PATCH v5 2/7] build: Link libgcc at the end of the link options list

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Reviewed-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>

On 4/9/20 4:19 AM, Jia He wrote:
> To use newlib on arm64 plat kvm, libgcc should be linked at the end of
> the options list, otherwise it will be ignored due to -stdlib.
>
> Without this patch, there will be a linking error on arm kvm plat:
> syslog.c:(.text+0x7d5cc): undefined reference to `__floatsitf'
> syslog.c:(.text+0x7d5cc): relocation truncated to fit: R_AARCH64_CALL26 against 
> undefined symbol `__floatsitf'
> /root/hj/UK/unikraft_upstream/apps/helloworld/build/helloworld_kvm-arm64.o: In 
> function `__ieee754_hypotl':
> syslog.c:(.text+0x99434): undefined reference to `__multf3'
> syslog.c:(.text+0x99434): relocation truncated to fit: R_AARCH64_CALL26 against 
> undefined symbol `__multf3'
> syslog.c:(.text+0x99444): undefined reference to `__multf3'
> syslog.c:(.text+0x99444): additional relocation overflows omitted from the 
> output
> syslog.c:(.text+0x99450): undefined reference to `__addtf3'
> /root/hj/UK/unikraft_upstream/apps/helloworld/build/helloworld_kvm-arm64.o: In 
> function `sqrtl':
> syslog.c:(.text+0xb12c0): undefined reference to `__trunctfdf2'
> syslog.c:(.text+0xb12c8): undefined reference to `__extenddftf2'
>
> Above undefined symbols are at libgcc.a
>
> Signed-off-by: Jia He <justin.he@xxxxxxx>
> ---
>   plat/kvm/Linker.uk | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/plat/kvm/Linker.uk b/plat/kvm/Linker.uk
> index 5e42193..65a5f8e 100644
> --- a/plat/kvm/Linker.uk
> +++ b/plat/kvm/Linker.uk
> @@ -2,6 +2,7 @@ ifeq (x86_64,$(CONFIG_UK_ARCH))
>   KVM_LDFLAGS-y += -Wl,-m,elf_x86_64
>   else ifeq (arm64,$(CONFIG_UK_ARCH))
>   KVM_LDFLAGS-y  += -Wl,-m,aarch64elf
> +KVM_LINK_LIBGCC_FLAG   := -lgcc
>   endif
>   
>   
> @@ -26,6 +27,7 @@ $(KVM_DEBUG_IMAGE): $(KVM_ALIBS) $(KVM_ALIBS-y) $(KVM_OLIBS) $(KVM_OLIBS-y) \
>                         -Wl$(comma)--start-group \
>                         $(KVM_ALIBS) $(KVM_ALIBS-y) \
>                         $(UK_ALIBS) $(UK_ALIBS-y) \
> +                       $(KVM_LINK_LIBGCC_FLAG) \
>                         -Wl$(comma)--end-group \
>                         -o $(KVM_IMAGE).ld.o)
>         $(call build_cmd,OBJCOPY,,$(KVM_IMAGE).o,\