Re: [Minios-devel] [UNIKRAFT PATCH v3 2/7] build: Link libgcc at the end of the link options list

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Hello Justin,

Please find the comment inline.

Thanks & Regards

Sharan

On 4/2/20 6:18 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) \
> +                       $(KVM_LINK_LIBGCC_FLAG) \
I think it is fine if we could directly include the libgcc.a into our 
statically built binary as this come GPL v3. Do you know if this has an 
impact on the BSD license?
>                         -Wl$(comma)--end-group \
>                         -o $(KVM_IMAGE).ld.o)
>         $(call build_cmd,OBJCOPY,,$(KVM_IMAGE).o,\
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