Re: [Minios-devel] [PATCH 37/40] arm64: add the makefile

[Steve Capper <steve.capper@xxxxxxx>]

On Tue, Nov 07, 2017 at 04:32:36PM +0800, Huang Shijie wrote:
> On Mon, Nov 06, 2017 at 06:00:30PM +0000, Julien Grall wrote:
> > Hi Shijie,
> > 
> > On 03/11/17 03:12, Huang Shijie wrote:
> > > Add the makefile for arm64 code.
> > > 
> > > This patch refers to Chen Baozi's patch:
> > >       "Initial codes for arm64"
> > > 
> > > Change-Id: I8fab7db2fe0d24d700e8be2dc9477e5812d6643b
> > > Jira: ENTOS-247
> > > Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
> > > ---
> > >   arch/arm/arm64/Makefile | 26 ++++++++++++++++++++++++++
> > >   arch/arm/arm64/arch.mk  |  7 +++++++
> > >   2 files changed, 33 insertions(+)
> > >   create mode 100644 arch/arm/arm64/Makefile
> > >   create mode 100644 arch/arm/arm64/arch.mk
> > > 
> > > diff --git a/arch/arm/arm64/Makefile b/arch/arm/arm64/Makefile
> > > new file mode 100644
> > > index 0000000..f268441
> > > --- /dev/null
> > > +++ b/arch/arm/arm64/Makefile
> > > @@ -0,0 +1,26 @@
> > > +#
> > > +# ARM architecture specific makefiles.
> > > +#
> > > +TOPLEVEL_DIR = $(CURDIR)/../../..
> > > +OBJ_DIR=$(CURDIR)
> > > +
> > > +include ../../../Config.mk
> > > +include ../../../minios.mk
> > > +
> > > +ifeq ($(MINIOS_TARGET_ARCH),arm64)
> > > +src-y += ../setup.c ../mm.c ../sched.c ../gic.c ../events.c ../time.c 
> > > traps.c
> > 
> > This is really ugly and clearly show the lack of cohesion between arm64 and
> > arm32. You would not need that if the directory arm where containing only
> > common code.
> Okay, I will try to move it to some common place with the arm32..
> 
> > 
> > > +src-$(CONFIG_BALLOON) += ../balloon.c
> > > +
> > > +ARCH_OBJS := $(patsubst %.c,$(OBJ_DIR)/%.o,$(src-y))
> > > +ARCH_OBJS += $(OBJ_DIR)/hypercalls64.o
> > > +endif
> > > +
> > > +all: $(OBJ_DIR)/$(ARCH_LIB)
> > > +
> > > +# $(HEAD_ARCH_OBJ) is only built here, needed on linking
> > > +# in ../../Makefile.
> > > +$(OBJ_DIR)/$(ARCH_LIB): $(ARCH_OBJS) $(OBJ_DIR)/$(HEAD_ARCH_OBJ)
> > > + $(AR) rv $(OBJ_DIR)/$(ARCH_LIB) $(ARCH_OBJS)
> > > +
> > > +clean:
> > > + rm -f $(OBJ_DIR)/$(ARCH_LIB) $(ARCH_OBJS) $(OBJ_DIR)/$(HEAD_ARCH_OBJ)
> > > diff --git a/arch/arm/arm64/arch.mk b/arch/arm/arm64/arch.mk
> > > new file mode 100644
> > > index 0000000..28e1d9c
> > > --- /dev/null
> > > +++ b/arch/arm/arm64/arch.mk
> > > @@ -0,0 +1,7 @@
> > > +ifeq ($(MINIOS_TARGET_ARCH),arm64)
> > > +ARCH_CFLAGS  := -D__aarch64__ -DXEN_HAVE_PV_GUEST_ENTRY 
> > > -mgeneral-regs-only -fno-PIE
> > 
> > Why do you need to define __aarch64__? The compiler should to it for you.
> Yes. we can remove it.
> > 
> > Why do you define XEN_HAVE_PV_GUEST_ENTRY? Arm does not have any start_info
> > page.
> okay, I will remove.
> 
> > 
> > Lastly, why -fno-PIE?
> Steve tested a platform which compile very slowly, and need the -fno-PIE
> for it.

Hi,

-fno-PIE is needed when building with a Debian Stretch or newer toolchain,
as these are configured with: --enable-default-pie

If we omit -fno-PIE then a global object table is used where we are not
expecting it and this results in crashes in the early code as uninitialised
pointers are dereferenced.

Cheers,
-- 
Steve

> 
> thanks
> Huang Shijie

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