From: Keir Fraser <keir.fraser@citrix.com>
Date: Wed, 10 Feb 2010 09:20:56 +0000 (+0000)
Subject: x86: move trampoline location
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~12622
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=e9603f14e3ddf91f2838a6798fab3897fe069259;p=xen.git

x86: move trampoline location

A partner of ours is reporting boot failures (Xen not even emitting a
single message) over iSCSI on new (UEFI based) systems. After
pointing at their BIOS initially I finally remembered to take a look
at the memory map a native kernel booted this way see - and voila, the
BIOS reports memory starting at 0x8d000 as reserved. Xen, however,
places about 12k of (trampoline) data at 0x8c000.

For now, move the trampolien down by 4kB to 0x88000. Later we may
choose the location dynamically based on E820 information, if this
proves to be an ongoing problem.

One thing this patch enforces in any case is a single point of
definition for the hard coded location, so that at least adjusting it
won't require more than a single line change in the future.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
---

diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
index d9a7c3f963..90856f918e 100644
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -2,6 +2,8 @@ obj-y += head.o
 
 head.o: reloc.S
 
-# NB. BOOT_TRAMPOLINE == 0x8c000
+BOOT_TRAMPOLINE := $(shell sed -n 's,^\#define[[:space:]]\+BOOT_TRAMPOLINE[[:space:]]\+,,p' $(BASEDIR)/include/asm-x86/config.h)
 %.S: %.c
-	RELOC=0x8c000 $(MAKE) -f build32.mk $@
+	RELOC=$(BOOT_TRAMPOLINE) $(MAKE) -f build32.mk $@
+
+reloc.S: $(BASEDIR)/include/asm-x86/config.h
diff --git a/xen/arch/x86/boot/build32.mk b/xen/arch/x86/boot/build32.mk
index a570d42524..01f7480b52 100644
--- a/xen/arch/x86/boot/build32.mk
+++ b/xen/arch/x86/boot/build32.mk
@@ -19,7 +19,9 @@ CFLAGS += -Werror -fno-builtin -msoft-float
 	$(OBJCOPY) -O binary $< $@
 
 %.lnk: %.o
-	$(LD) $(LDFLAGS_DIRECT) -N -Ttext 0x8c000 -o $@ $<
+	$(LD) $(LDFLAGS_DIRECT) -N -Ttext $(RELOC) -o $@ $<
 
 %.o: %.c
 	$(CC) $(CFLAGS) -c $< -o $@
+
+reloc.o: $(BASEDIR)/include/asm-x86/config.h
diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h
index 8c9b3c1d9e..76539359c5 100644
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -94,7 +94,7 @@
 /* Primary stack is restricted to 8kB by guard pages. */
 #define PRIMARY_STACK_SIZE 8192
 
-#define BOOT_TRAMPOLINE 0x8c000
+#define BOOT_TRAMPOLINE 0x88000
 #define bootsym_phys(sym)                                 \
     (((unsigned long)&(sym)-(unsigned long)&trampoline_start)+BOOT_TRAMPOLINE)
 #define bootsym(sym)                                      \