[v3,3/3] x86: check for multiboot{1, 2} header presence
diff mbox series

Message ID 20190627093335.56355-3-roger.pau@citrix.com
State New, archived
Headers show
Series
  • [v3,1/3] x86/linker: add a reloc section to ELF linker script
Related show

Commit Message

Roger Pau Monné June 27, 2019, 9:33 a.m. UTC
After building the hypervisor binary. Note that the check is performed
by searching for the magic header value at the start of the binary.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wl@xen.org>
---
Changes since v2:
 - Use a variable to store the intermediate file name.
 - Remove the intermediate file in the clean target.
 - Add intermediate file to gitignore.

Changes since v1:
 - Use an intermediate file to perform the header checks.
---
 .gitignore            | 1 +
 xen/arch/x86/Makefile | 9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

Comments

Jan Beulich June 27, 2019, 11:26 a.m. UTC | #1
>>> On 27.06.19 at 11:33, <roger.pau@citrix.com> wrote:
> After building the hypervisor binary. Note that the check is performed
> by searching for the magic header value at the start of the binary.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Acked-by: Jan Beulich <jbeulich@suse.com>
Andrew Cooper June 27, 2019, 11:51 a.m. UTC | #2
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
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  </head>
  <body text="#000000" bgcolor="#FFFFFF">
    <div class="moz-cite-prefix">On 27/06/2019 10:33, Roger Pau Monne
      wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:20190627093335.56355-3-roger.pau@citrix.com">
      <pre class="moz-quote-pre" wrap="">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)</pre>
    </blockquote>
    <br>
    I'd suggest giving this a .elf32 suffix to make it clear which pass
    of the build it comes from.<br>
    <br>
    <blockquote type="cite"
      cite="mid:20190627093335.56355-3-roger.pau@citrix.com">
      <pre class="moz-quote-pre" wrap="">
 $(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 &gt; /dev/null ||
+	od -t x4 -N 32768 $(TMP) | grep e85250d6 &gt; /dev/null</pre>
    </blockquote>
    <br>
    This works, but <br>
    <br>
    Makefile:104: recipe for target '/local/xen.git/xen/xen' failed<br>
    <br>
    Isn't helpful to identify what went wrong.  Sadly, we can't use
    $(error ...) in a shell snippet, but:<br>
    <br>
    <pre><a class="moz-txt-link-abbreviated" href="mailto:andrewcoop@andrewcoop:/local/xen.git/xen$">andrewcoop@andrewcoop:/local/xen.git/xen$</a> git d
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 94e6c9aee3..a1d6605a8b 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -99,13 +99,14 @@ endif
 syms-warn-dup-y := --warn-dup
 syms-warn-dup-$(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 &gt; /dev/null
-       od -t x4 -N 32768 $(TMP) | grep e85250d6 &gt; /dev/null
+       od -t x4 -N 8192 $(TMP)  | grep 1badb002 &gt; /dev/null || \
+               { echo "No Multiboot1 header found"; false; }
+       od -t x4 -N 32768 $(TMP) | grep e85250d6 &gt; /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)

</pre>
    results in:<br>
    <br>
    No Multiboot1 header found<br>
    Makefile:104: recipe for target '/local/xen.git/xen/xen' failed<br>
    make[2]: *** [/local/xen.git/xen/xen] Error 1<br>
    Makefile:136: recipe for target '/local/xen.git/xen/xen' failed<br>
    make[1]: *** [/local/xen.git/xen/xen] Error 2<br>
    Makefile:45: recipe for target 'build' failed<br>
    make: *** [build] Error 2<br>
    <br>
    Which is far more clear.<br>
    <br>
    Thoughts?<br>
    <br>
    ~Andrew<br>
  </body>
</html>
Jan Beulich June 27, 2019, 12:10 p.m. UTC | #3
>>> On 27.06.19 at 13:51, <andrew.cooper3@citrix.com> wrote:
> 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,

I think we could:

       $(if $(shell od -t x4 -N 8192 $(TMP) | grep 1badb002),,$(error ...)exit 1)

But I admit I didn't check whether it is well defined that only one of
the last two operands of $(if ) get actually evaluated.

> 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?

Good idea. The only further request I have is to add >&2 to the
echo commands (unless we go the $(error ) route anyway).

Jan
Andrew Cooper June 27, 2019, 12:36 p.m. UTC | #4
On 27/06/2019 13:10, Jan Beulich wrote:
>>>> On 27.06.19 at 13:51, <andrew.cooper3@citrix.com> wrote:
>> 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,
> I think we could:
>
>        $(if $(shell od -t x4 -N 8192 $(TMP) | grep 1badb002),,$(error ...)exit 1)
>
> But I admit I didn't check whether it is well defined that only one of
> the last two operands of $(if ) get actually evaluated.

Of the two options, I think the || { ; false } is clearer to follow.

>
>> 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?
> Good idea. The only further request I have is to add >&2 to the
> echo commands.

Done.

~Andrew
Roger Pau Monné June 27, 2019, 1:08 p.m. UTC | #5
On Thu, Jun 27, 2019 at 12:51:05PM +0100, Andrew Cooper wrote:
> 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.

That's fine, please also adjust the ignored list and the clean
target.

> >  $(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?

Thanks, is indeed better. I also agree with Jan on the
redirection to stderr.

Roger.

Patch
diff mbox series

diff --git a/.gitignore b/.gitignore
index a77cbff02c..56bcb64837 100644
--- a/.gitignore
+++ b/.gitignore
@@ -278,6 +278,7 @@  tools/xentrace/xentrace
 xen/.banner
 xen/.config
 xen/.config.old
+xen/.xen
 xen/System.map
 xen/arch/x86/asm-macros.i
 xen/arch/x86/boot/mkelf32
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)
 $(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
+	mv $(TMP) $(TARGET)
 
 ALL_OBJS := $(BASEDIR)/arch/x86/boot/built_in.o $(BASEDIR)/arch/x86/efi/built_in.o $(ALL_OBJS)
 
@@ -249,7 +254,7 @@  efi/mkreloc: efi/mkreloc.c
 clean::
 	rm -f asm-offsets.s *.lds boot/*.o boot/*~ boot/core boot/mkelf32
 	rm -f asm-macros.i $(BASEDIR)/include/asm-x86/asm-macros.*
-	rm -f $(BASEDIR)/.xen-syms.[0-9]* boot/.*.d
+	rm -f $(BASEDIR)/.xen-syms.[0-9]* boot/.*.d $(BASEDIR)/.xen
 	rm -f $(BASEDIR)/.xen.efi.[0-9]* efi/*.efi efi/mkreloc
 	rm -f boot/cmdline.S boot/reloc.S boot/*.lnk boot/*.bin
 	rm -f note.o