Re: [Xen-devel] [PATCH v3 3/3] x86: check for multiboot{1, 2} header presence

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 27/06/2019 10:33, Roger Pau Monne wrote:

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 8a8d8f060f..94e6c9aee3 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -99,9 +99,14 @@ endif
 syms-warn-dup-y := --warn-dup
 syms-warn-dup-$(CONFIG_SUPPRESS_DUPLICATE_SYMBOL_WARNINGS) :=
 
+$(TARGET): TMP = $(@D)/.$(@F)

I'd suggest giving this a .elf32 suffix to make it clear which pass of the build it comes from.

 $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
-	./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TARGET) $(XEN_IMG_OFFSET) \
+	./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TMP) $(XEN_IMG_OFFSET) \
 	               `$(NM) $(TARGET)-syms | sed -ne 's/^\([^ ]*\) . __2M_rwdata_end$$/0x\1/p'`
+	# Check for multiboot{1,2} headers
+	od -t x4 -N 8192 $(TMP) | grep 1badb002 > /dev/null ||
+	od -t x4 -N 32768 $(TMP) | grep e85250d6 > /dev/null

This works, but

Makefile:104: recipe for target '/local/xen.git/xen/xen' failed

Isn't helpful to identify what went wrong.  Sadly, we can't use $(error ...) in a shell snippet, but:

andrewcoop@andrewcoop:/local/xen.git/xen$ git d
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 94e6c9aee3..a1d6605a8b 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -99,13 +99,14 @@ endif
 syms-warn-dup-y := --warn-dup
 syms-warn-dup-$(CONFIG_SUPPRESS_DUPLICATE_SYMBOL_WARNINGS) :=
 
-$(TARGET): TMP = $(@D)/.$(@F)
+$(TARGET): TMP = $(@D)/.$(@F).elf32
 $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
        ./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TMP) $(XEN_IMG_OFFSET) \
                       `$(NM) $(TARGET)-syms | sed -ne 's/^\([^ ]*\) . __2M_rwdata_end$$/0x\1/p'`
-       # Check for multiboot{1,2} headers
-       od -t x4 -N 8192 $(TMP) | grep 1badb002 > /dev/null
-       od -t x4 -N 32768 $(TMP) | grep e85250d6 > /dev/null
+       od -t x4 -N 8192 $(TMP)  | grep 1badb002 > /dev/null || \
+               { echo "No Multiboot1 header found"; false; }
+       od -t x4 -N 32768 $(TMP) | grep e85250d6 > /dev/null || \
+               { echo "No Multiboot2 header found"; false; }
        mv $(TMP) $(TARGET)
 
 ALL_OBJS := $(BASEDIR)/arch/x86/boot/built_in.o $(BASEDIR)/arch/x86/efi/built_in.o $(ALL_OBJS)

results in:

No Multiboot1 header found
Makefile:104: recipe for target '/local/xen.git/xen/xen' failed
make[2]: *** [/local/xen.git/xen/xen] Error 1
Makefile:136: recipe for target '/local/xen.git/xen/xen' failed
make[1]: *** [/local/xen.git/xen/xen] Error 2
Makefile:45: recipe for target 'build' failed
make: *** [build] Error 2

Which is far more clear.

Thoughts?

~Andrew

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