Re: [Minios-devel] [UNIKRAFT PATCHv5 16/46] plat/kvm: Generate linker scripts from source code

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hey Wei,

I am currently thinking of a nicer solution for linker scripts that have 
to be pre-processed. I think also other platforms could benefit from 
something like this. The build system should provide you an easy way to 
let you do this. Let me come up with a patch tomorrow to achieve this. 
You could then just use this one.
On 10.08.2018 09:08, Wei Chen wrote:
> Sometimes, using a macro in linker script will be easier for people
> to see what is done. This means we will share macros with source code.
> So, generate linker script from a .S will help linker script to share
> macros with source code.
>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   plat/kvm/Linker.uk                       | 7 +++++--
>   plat/kvm/x86/{link64.ld => link64.lds.S} | 0
>   2 files changed, 5 insertions(+), 2 deletions(-)
>   rename plat/kvm/x86/{link64.ld => link64.lds.S} (100%)
>
> diff --git a/plat/kvm/Linker.uk b/plat/kvm/Linker.uk
> index 2292b03..fbadde2 100644
> --- a/plat/kvm/Linker.uk
> +++ b/plat/kvm/Linker.uk
> @@ -1,5 +1,6 @@
>   ifeq (x86_64,$(CONFIG_UK_ARCH))
> -KVM_LDSCRIPT  := -Wl,-T,$(CONFIG_UK_BASE)/plat/kvm/x86/link64.ld
> +KVM_LDSCRIPT  := -Wl,-T,$(CONFIG_UK_BASE)/plat/kvm/x86/link64.lds
> +KVM_LDSCRIPT_FLAGS := -Wl,-T,$(KVM_LDSCRIPT)
>   KVM_LDFLAGS-y += -Wl,-m,elf_x86_64
>   endif
>   
> @@ -14,8 +15,10 @@ $(KVM_IMAGE): $(KVM_LINK) $(KVM_LINK-y) $(UK_LINK) $(UK_LINK-y)
>         $(call build_cmd,OBJCOPY,,$@.o,\
>                $(OBJCOPY) -w -G kvmos_* -G _libkvmplat_entry $@.ld.o $@.o)
>   ifeq (x86_64,$(CONFIG_UK_ARCH))
> +       $(call build_cmd,CC,,link64.lds.o,\
> +              $(CC) -E $(ASINCLUDES) $(ASFLAGS) $(ASFLAGS-y) -P 
> $(KVM_LDSCRIPT).S -o $(KVM_LDSCRIPT))
This rule says that the generated linker script is not saved to the 
build directory. We should definitely avoid this since multiple projects 
may use the same unikraft source base. Project configurations may result 
in different linker scripts. Because of this, each project has its own 
build directory.
>         $(call build_cmd,LD,,$@,\
> -              $(LD) $(LDFLAGS) $(LDFLAGS-y) $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) 
> $(KVM_LDSCRIPT) $@.o -o $@)
> +              $(LD) $(LDFLAGS) $(LDFLAGS-y) $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) 
> $(KVM_LDSCRIPT_FLAGS) $@.o -o $@)
>   ifeq ($(CONFIG_OPTIMIZE_DBGFILE),y)
>         $(call build_cmd,OBJCOPY,,$@.dbg,\
>                $(OBJCOPY) --only-keep-debug $@ $@.dbg)
> diff --git a/plat/kvm/x86/link64.ld b/plat/kvm/x86/link64.lds.S
> similarity index 100%
> rename from plat/kvm/x86/link64.ld
> rename to plat/kvm/x86/link64.lds.S
Thanks,

Simon

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