* [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang
@ 2021-03-09 4:52 Bill Wendling
2021-04-27 21:15 ` Bill Wendling
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Bill Wendling @ 2021-03-09 4:52 UTC (permalink / raw)
To: kvm, pbonzini; +Cc: jmattson, Bill Wendling
The -nostdlib flag disables the driver from adding libclang_rt.*.a
during linking. Adding a specific library to the command line then
causes the linker to report unresolved symbols, because the libraries
that resolve those symbols aren't automatically added. Turns out clang
doesn't need to specify that library.
Signed-off-by: Bill Wendling <morbo@google.com>
---
Makefile | 6 ++++++
arm/Makefile.common | 2 ++
x86/Makefile.common | 2 ++
3 files changed, 10 insertions(+)
diff --git a/Makefile b/Makefile
index e0828fe..61a1276 100644
--- a/Makefile
+++ b/Makefile
@@ -22,10 +22,16 @@ DESTDIR := $(PREFIX)/share/kvm-unit-tests/
cc-option = $(shell if $(CC) -Werror $(1) -S -o /dev/null -xc /dev/null \
> /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
+# cc-name
+# Expands to either gcc or clang
+cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
+
#make sure env CFLAGS variable is not used
CFLAGS =
+ifneq ($(cc-name),clang)
libgcc := $(shell $(CC) --print-libgcc-file-name)
+endif
libcflat := lib/libcflat.a
cflatobjs := \
diff --git a/arm/Makefile.common b/arm/Makefile.common
index a123e85..94922aa 100644
--- a/arm/Makefile.common
+++ b/arm/Makefile.common
@@ -58,7 +58,9 @@ OBJDIRS += lib/arm
libeabi = lib/arm/libeabi.a
eabiobjs = lib/arm/eabi_compat.o
+ifneq ($(cc-name),clang)
libgcc := $(shell $(CC) $(machine) --print-libgcc-file-name)
+endif
FLATLIBS = $(libcflat) $(LIBFDT_archive) $(libgcc) $(libeabi)
%.elf: LDFLAGS = -nostdlib $(arch_LDFLAGS)
diff --git a/x86/Makefile.common b/x86/Makefile.common
index 55f7f28..a96b236 100644
--- a/x86/Makefile.common
+++ b/x86/Makefile.common
@@ -37,7 +37,9 @@ COMMON_CFLAGS += -O1
# stack.o relies on frame pointers.
KEEP_FRAME_POINTER := y
+ifneq ($(cc-name),clang)
libgcc := $(shell $(CC) -m$(bits) --print-libgcc-file-name)
+endif
# We want to keep intermediate file: %.elf and %.o
.PRECIOUS: %.elf %.o
--
2.30.1.766.gb4fecdf3b7-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang
2021-03-09 4:52 [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang Bill Wendling
@ 2021-04-27 21:15 ` Bill Wendling
2021-05-04 17:07 ` Jim Mattson
2021-05-05 12:31 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Bill Wendling @ 2021-04-27 21:15 UTC (permalink / raw)
To: kvm list, Paolo Bonzini; +Cc: Jim Mattson
Ping.
On Mon, Mar 8, 2021 at 8:53 PM Bill Wendling <morbo@google.com> wrote:
>
> The -nostdlib flag disables the driver from adding libclang_rt.*.a
> during linking. Adding a specific library to the command line then
> causes the linker to report unresolved symbols, because the libraries
> that resolve those symbols aren't automatically added. Turns out clang
> doesn't need to specify that library.
>
> Signed-off-by: Bill Wendling <morbo@google.com>
> ---
> Makefile | 6 ++++++
> arm/Makefile.common | 2 ++
> x86/Makefile.common | 2 ++
> 3 files changed, 10 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index e0828fe..61a1276 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -22,10 +22,16 @@ DESTDIR := $(PREFIX)/share/kvm-unit-tests/
> cc-option = $(shell if $(CC) -Werror $(1) -S -o /dev/null -xc /dev/null \
> > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
>
> +# cc-name
> +# Expands to either gcc or clang
> +cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
> +
> #make sure env CFLAGS variable is not used
> CFLAGS =
>
> +ifneq ($(cc-name),clang)
> libgcc := $(shell $(CC) --print-libgcc-file-name)
> +endif
>
> libcflat := lib/libcflat.a
> cflatobjs := \
> diff --git a/arm/Makefile.common b/arm/Makefile.common
> index a123e85..94922aa 100644
> --- a/arm/Makefile.common
> +++ b/arm/Makefile.common
> @@ -58,7 +58,9 @@ OBJDIRS += lib/arm
> libeabi = lib/arm/libeabi.a
> eabiobjs = lib/arm/eabi_compat.o
>
> +ifneq ($(cc-name),clang)
> libgcc := $(shell $(CC) $(machine) --print-libgcc-file-name)
> +endif
>
> FLATLIBS = $(libcflat) $(LIBFDT_archive) $(libgcc) $(libeabi)
> %.elf: LDFLAGS = -nostdlib $(arch_LDFLAGS)
> diff --git a/x86/Makefile.common b/x86/Makefile.common
> index 55f7f28..a96b236 100644
> --- a/x86/Makefile.common
> +++ b/x86/Makefile.common
> @@ -37,7 +37,9 @@ COMMON_CFLAGS += -O1
> # stack.o relies on frame pointers.
> KEEP_FRAME_POINTER := y
>
> +ifneq ($(cc-name),clang)
> libgcc := $(shell $(CC) -m$(bits) --print-libgcc-file-name)
> +endif
>
> # We want to keep intermediate file: %.elf and %.o
> .PRECIOUS: %.elf %.o
> --
> 2.30.1.766.gb4fecdf3b7-goog
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang
2021-03-09 4:52 [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang Bill Wendling
2021-04-27 21:15 ` Bill Wendling
@ 2021-05-04 17:07 ` Jim Mattson
2021-05-05 12:31 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Jim Mattson @ 2021-05-04 17:07 UTC (permalink / raw)
To: Bill Wendling; +Cc: kvm list, Paolo Bonzini
On Mon, Mar 8, 2021 at 8:53 PM Bill Wendling <morbo@google.com> wrote:
>
> The -nostdlib flag disables the driver from adding libclang_rt.*.a
> during linking. Adding a specific library to the command line then
> causes the linker to report unresolved symbols, because the libraries
> that resolve those symbols aren't automatically added. Turns out clang
> doesn't need to specify that library.
>
> Signed-off-by: Bill Wendling <morbo@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang
2021-03-09 4:52 [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang Bill Wendling
2021-04-27 21:15 ` Bill Wendling
2021-05-04 17:07 ` Jim Mattson
@ 2021-05-05 12:31 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2021-05-05 12:31 UTC (permalink / raw)
To: Bill Wendling, kvm; +Cc: jmattson
On 09/03/21 05:52, Bill Wendling wrote:
> The -nostdlib flag disables the driver from adding libclang_rt.*.a
> during linking. Adding a specific library to the command line then
> causes the linker to report unresolved symbols, because the libraries
> that resolve those symbols aren't automatically added. Turns out clang
> doesn't need to specify that library.
This breaks 32-bit build with clang due to __udivdi3/__umoddi3. Let me
post an alternative.
Paolo
> Signed-off-by: Bill Wendling <morbo@google.com>
> ---
> Makefile | 6 ++++++
> arm/Makefile.common | 2 ++
> x86/Makefile.common | 2 ++
> 3 files changed, 10 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index e0828fe..61a1276 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -22,10 +22,16 @@ DESTDIR := $(PREFIX)/share/kvm-unit-tests/
> cc-option = $(shell if $(CC) -Werror $(1) -S -o /dev/null -xc /dev/null \
> > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
>
> +# cc-name
> +# Expands to either gcc or clang
> +cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
> +
> #make sure env CFLAGS variable is not used
> CFLAGS =
>
> +ifneq ($(cc-name),clang)
> libgcc := $(shell $(CC) --print-libgcc-file-name)
> +endif
>
> libcflat := lib/libcflat.a
> cflatobjs := \
> diff --git a/arm/Makefile.common b/arm/Makefile.common
> index a123e85..94922aa 100644
> --- a/arm/Makefile.common
> +++ b/arm/Makefile.common
> @@ -58,7 +58,9 @@ OBJDIRS += lib/arm
> libeabi = lib/arm/libeabi.a
> eabiobjs = lib/arm/eabi_compat.o
>
> +ifneq ($(cc-name),clang)
> libgcc := $(shell $(CC) $(machine) --print-libgcc-file-name)
> +endif
>
> FLATLIBS = $(libcflat) $(LIBFDT_archive) $(libgcc) $(libeabi)
> %.elf: LDFLAGS = -nostdlib $(arch_LDFLAGS)
> diff --git a/x86/Makefile.common b/x86/Makefile.common
> index 55f7f28..a96b236 100644
> --- a/x86/Makefile.common
> +++ b/x86/Makefile.common
> @@ -37,7 +37,9 @@ COMMON_CFLAGS += -O1
> # stack.o relies on frame pointers.
> KEEP_FRAME_POINTER := y
>
> +ifneq ($(cc-name),clang)
> libgcc := $(shell $(CC) -m$(bits) --print-libgcc-file-name)
> +endif
>
> # We want to keep intermediate file: %.elf and %.o
> .PRECIOUS: %.elf %.o
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-05-05 12:31 UTC | newest]
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2021-03-09 4:52 [kvm-unit-tests PATCH] Makefile: do not use "libgcc" for clang Bill Wendling
2021-04-27 21:15 ` Bill Wendling
2021-05-04 17:07 ` Jim Mattson
2021-05-05 12:31 ` Paolo Bonzini
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