linux-kernel - Re: [PATCH 02/23] x86, realmode: realmode.bin infrastructure

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Date:	Tue, 08 May 2012 12:14:39 -0700
From:	"H. Peter Anvin" <hpa@...ux.intel.com>
To:	Sam Ravnborg <sam@...nborg.org>
CC:	Jarkko Sakkinen <jarkko.sakkinen@...el.com>,
	linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
	Michal Marek <mmarek@...e.cz>,
	Joseph Cihula <joseph.cihula@...el.com>,
	Shane Wang <shane.wang@...el.com>
Subject: Re: [PATCH 02/23] x86, realmode: realmode.bin infrastructure

On 05/08/2012 11:53 AM, Sam Ravnborg wrote:
+# How to compile the 16-bit code.  Note we always compile for -march=i386,
+# that way we can complain to the user if the CPU is insufficient.
+KBUILD_CFLAGS	:= $(LINUXINCLUDE) -m32 -g -Os -D_SETUP -D__KERNEL__ \
+		   -DDISABLE_BRANCH_PROFILING \
+		   -Wall -Wstrict-prototypes \
+		   -march=i386 -mregparm=3 \
+		   -include $(srctree)/$(src)/../../boot/code16gcc.h \
+		   -fno-strict-aliasing -fomit-frame-pointer \
+		   $(call cc-option, -ffreestanding) \
+		   $(call cc-option, -fno-toplevel-reorder,\
+			$(call cc-option, -fno-unit-at-a-time)) \
+		   $(call cc-option, -fno-stack-protector) \
+		   $(call cc-option, -mpreferred-stack-boundary=2)
+KBUILD_AFLAGS	:= $(KBUILD_CFLAGS) -D__ASSEMBLY__


> 
> How much is needed to avoid this misuse of kernel-internal build rules?
> This was and is an ugly hack.
> 

It is more or less the same as for arch/x86/boot and other things.  If
there are better ways to do it suggestions are very much appreciated.

However, it is a bit of a tricky bit because we need *some* of the bits
of the target compiler configuration and some not (this is the same as
arch/x86/boot etc.)  It is not "pure target" but it's also most
definitely not host.

	-hpa
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