[PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells

[PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells

[Alexander Clouter]

Counter to the documentation for the dash shell, it seems that on my
x86_64 filth under Debian only does 32bit math.  As I have configured my
lapdog to use 'dash' for non-interactive tasks I run into problems when
compiling a compressed kernel.

I play with the AR7 platform, so VMLINUX_LOAD_ADDRESS is
0xffffffff94100000, and for an example 4MiB kernel
VMLINUZ_LOAD_ADDRESS is made out to be:
----
alex@berk:~$ bash -c 'printf "%x\n" $((0xffffffff94100000 + 0x400000))'
ffffffff94500000
alex@berk:~$ dash -c 'printf "%x\n" $((0xffffffff94100000 + 0x400000))'
80000000003fffff
----

The former is obviously correct whilst the later breaks things royally.

Fortunately working with only the lower 32bit's works for both bash and
dash:
----
$ bash -c 'printf "%x\n" $((0x94100000 + 0x400000))'
94500000
$ dash -c 'printf "%x\n" $((0x94100000 + 0x400000))'
94500000
----

So, we can split the original 64bit string to two parts, and only
calculate the low 32bit part, which is big enough (1GiB kernel sizes
anyone?) for a normal Linux kernel image file, now, we calculate the
VMLINUZ_LOAD_ADDRESS like this:

1. if present, append top 32bit of VMLINUX_LOAD_ADDRESS" as a prefix
2. get the sum of the low 32bit of VMLINUX_LOAD_ADDRESS + VMLINUX_SIZE

This patch fixes vmlinuz kernel builds on systems where only a 
32bit-only math shell is available.

Patch Changelog:
  Version 2
    - simplified method by using 'expr' for 'substr' and making it work 
	with dash once again
  Version 1
    - Revert the removals of '-n "$(VMLINUX_SIZE)"' to avoid the error  
        of "make clean"
    - Consider more cases of the VMLINUX_LOAD_ADDRESS
  Version 0
    - initial release

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Acked-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
 arch/mips/boot/compressed/Makefile |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index 671d344..ab78095 100644
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -14,8 +14,11 @@
 
 # compressed kernel load addr: VMLINUZ_LOAD_ADDRESS > VMLINUX_LOAD_ADDRESS + VMLINUX_SIZE
 VMLINUX_SIZE := $(shell wc -c $(objtree)/$(KBUILD_IMAGE) 2>/dev/null | cut -d' ' -f1)
-VMLINUX_SIZE := $(shell [ -n "$(VMLINUX_SIZE)" ] && echo $$(($(VMLINUX_SIZE) + (65536 - $(VMLINUX_SIZE) % 65536))))
-VMLINUZ_LOAD_ADDRESS := 0x$(shell [ -n "$(VMLINUX_SIZE)" ] && printf %x $$(($(VMLINUX_LOAD_ADDRESS) + $(VMLINUX_SIZE))))
+VMLINUX_SIZE := $(shell [ -n "$(VMLINUX_SIZE)" ] && echo -n $$(($(VMLINUX_SIZE) + (65536 - $(VMLINUX_SIZE) % 65536))))
+# VMLINUZ_LOAD_ADDRESS = concat "high32 of VMLINUX_LOAD_ADDRESS" and "(low32 of VMLINUX_LOAD_ADDRESS) + VMLINUX_SIZE"
+HIGH32 := $(shell A=$(VMLINUX_LOAD_ADDRESS); [ $${\#A} -gt 10 ] && expr substr "$(VMLINUX_LOAD_ADDRESS)" 3 $$(($${\#A} - 10)))
+LOW32 := $(shell [ -n "$(HIGH32)" ] && A=11 || A=3; expr substr "$(VMLINUX_LOAD_ADDRESS)" $${A} 8)
+VMLINUZ_LOAD_ADDRESS := 0x$(shell [ -n "$(VMLINUX_SIZE)" -a -n "$(LOW32)" ] && printf "$(HIGH32)%08x" $$(($(VMLINUX_SIZE) + 0x$(LOW32))))
 
 # set the default size of the mallocing area for decompressing
 BOOT_HEAP_SIZE := 0x400000
-- 
1.6.6

Re: [PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells

[Wu Zhangjin]

Hi, Ralf

This patch is a bugfix, which is necessary for the users who are using
dash(or the other SHELLs not compatible with bash). without it, they
will get a broken compressed kernel image(with wrong load address).

Could you please queue it for 2.6.34 and also 2.6.33?

Thanks & Regards,
	Wu Zhangjin

On Wed, 2010-01-20 at 20:50 +0000, Alexander Clouter wrote:
> Counter to the documentation for the dash shell, it seems that on my
> x86_64 filth under Debian only does 32bit math.  As I have configured my
> lapdog to use 'dash' for non-interactive tasks I run into problems when
> compiling a compressed kernel.
> 
> I play with the AR7 platform, so VMLINUX_LOAD_ADDRESS is
> 0xffffffff94100000, and for an example 4MiB kernel
> VMLINUZ_LOAD_ADDRESS is made out to be:
> ----
> alex@berk:~$ bash -c 'printf "%x\n" $((0xffffffff94100000 + 0x400000))'
> ffffffff94500000
> alex@berk:~$ dash -c 'printf "%x\n" $((0xffffffff94100000 + 0x400000))'
> 80000000003fffff
> ----
> 
> The former is obviously correct whilst the later breaks things royally.
> 
> Fortunately working with only the lower 32bit's works for both bash and
> dash:
> ----
> $ bash -c 'printf "%x\n" $((0x94100000 + 0x400000))'
> 94500000
> $ dash -c 'printf "%x\n" $((0x94100000 + 0x400000))'
> 94500000
> ----
> 
> So, we can split the original 64bit string to two parts, and only
> calculate the low 32bit part, which is big enough (1GiB kernel sizes
> anyone?) for a normal Linux kernel image file, now, we calculate the
> VMLINUZ_LOAD_ADDRESS like this:
> 
> 1. if present, append top 32bit of VMLINUX_LOAD_ADDRESS" as a prefix
> 2. get the sum of the low 32bit of VMLINUX_LOAD_ADDRESS + VMLINUX_SIZE
> 
> This patch fixes vmlinuz kernel builds on systems where only a 
> 32bit-only math shell is available.
> 
> Patch Changelog:
>   Version 2
>     - simplified method by using 'expr' for 'substr' and making it work 
> 	with dash once again
>   Version 1
>     - Revert the removals of '-n "$(VMLINUX_SIZE)"' to avoid the error  
>         of "make clean"
>     - Consider more cases of the VMLINUX_LOAD_ADDRESS
>   Version 0
>     - initial release
> 
> Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
> Acked-by: Wu Zhangjin <wuzhangjin@gmail.com>
> ---
>  arch/mips/boot/compressed/Makefile |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
> index 671d344..ab78095 100644
> --- a/arch/mips/boot/compressed/Makefile
> +++ b/arch/mips/boot/compressed/Makefile
> @@ -14,8 +14,11 @@
>  
>  # compressed kernel load addr: VMLINUZ_LOAD_ADDRESS > VMLINUX_LOAD_ADDRESS + VMLINUX_SIZE
>  VMLINUX_SIZE := $(shell wc -c $(objtree)/$(KBUILD_IMAGE) 2>/dev/null | cut -d' ' -f1)
> -VMLINUX_SIZE := $(shell [ -n "$(VMLINUX_SIZE)" ] && echo $$(($(VMLINUX_SIZE) + (65536 - $(VMLINUX_SIZE) % 65536))))
> -VMLINUZ_LOAD_ADDRESS := 0x$(shell [ -n "$(VMLINUX_SIZE)" ] && printf %x $$(($(VMLINUX_LOAD_ADDRESS) + $(VMLINUX_SIZE))))
> +VMLINUX_SIZE := $(shell [ -n "$(VMLINUX_SIZE)" ] && echo -n $$(($(VMLINUX_SIZE) + (65536 - $(VMLINUX_SIZE) % 65536))))
> +# VMLINUZ_LOAD_ADDRESS = concat "high32 of VMLINUX_LOAD_ADDRESS" and "(low32 of VMLINUX_LOAD_ADDRESS) + VMLINUX_SIZE"
> +HIGH32 := $(shell A=$(VMLINUX_LOAD_ADDRESS); [ $${\#A} -gt 10 ] && expr substr "$(VMLINUX_LOAD_ADDRESS)" 3 $$(($${\#A} - 10)))
> +LOW32 := $(shell [ -n "$(HIGH32)" ] && A=11 || A=3; expr substr "$(VMLINUX_LOAD_ADDRESS)" $${A} 8)
> +VMLINUZ_LOAD_ADDRESS := 0x$(shell [ -n "$(VMLINUX_SIZE)" -a -n "$(LOW32)" ] && printf "$(HIGH32)%08x" $$(($(VMLINUX_SIZE) + 0x$(LOW32))))
>  
>  # set the default size of the mallocing area for decompressing
>  BOOT_HEAP_SIZE := 0x400000

Re: [PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells

[Ralf Baechle]

On Wed, Jan 20, 2010 at 08:50:07PM +0000, Alexander Clouter wrote:

> Counter to the documentation for the dash shell, it seems that on my
> x86_64 filth under Debian only does 32bit math.  As I have configured my

POSIX apparently specifies at least "long" type arithmetic for shells, so
if your dash indeed is a 64-bit binary it's in violation of POSIX.  What
does

  file $(which $SHELL)

say?

The dash binary on my Fedora 12 i386 seems to perform 64-bit arithmetic.

  Ralf

Re: [PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells

[Alexander Clouter]

Hi,

* Ralf Baechle <ralf@linux-mips.org> [2010-01-22 15:52:56+0100]:
>
> On Wed, Jan 20, 2010 at 08:50:07PM +0000, Alexander Clouter wrote:
> 
> > Counter to the documentation for the dash shell, it seems that on my
> > x86_64 filth under Debian only does 32bit math.  As I have configured my
> 
> POSIX apparently specifies at least "long" type arithmetic for shells, so
> if your dash indeed is a 64-bit binary it's in violation of POSIX.
>
/me points to the 'Counter to the documentation for the dash shell...' 
	he put in his description...

> What does
> 
>   file $(which $SHELL)
> 
> say?
> 
Well, 'bash' (x86-64) as thats my *interactive* shell, I use dash for 
the non-interactive stuff.

> The dash binary on my Fedora 12 i386 seems to perform 64-bit arithmetic.
> 
...does it really matter, we still are leaving all the 32bit users out 
there in the lurch?

When I get around to looking at the problem further I'll report it to 
the Debian folk...meanwhile, builds on 32bit math only shells is broken 
for vmlinuz regardless of my borkened shell :)

Cheers

-- 
Alexander Clouter
.sigmonster says:   We are not anticipating any emergencies.

Re: [PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells

[Wu Zhangjin]

On Fri, 2010-01-22 at 15:52 +0100, Ralf Baechle wrote:
> On Wed, Jan 20, 2010 at 08:50:07PM +0000, Alexander Clouter wrote:
> 
> > Counter to the documentation for the dash shell, it seems that on my
> > x86_64 filth under Debian only does 32bit math.  As I have configured my
> 
> POSIX apparently specifies at least "long" type arithmetic for shells, so
> if your dash indeed is a 64-bit binary it's in violation of POSIX.  What
> does
> 
>   file $(which $SHELL)
> 
> say?
> 
> The dash binary on my Fedora 12 i386 seems to perform 64-bit arithmetic.
> 

Hi, Ralf

on my yeeloong laptop, with dash(0.5.5.1-3) in o32 ABI, it also can only
execute 32-bit numbers, but on my thinkpad SL400(i686, dash version is
0.5.5.1-2), it works well with 64-bit arithmetic.

So, it means dash not always works normally, perhaps there is a bug
there, or the bug only exists on MIPS machines?

Best Regards,
	Wu Zhangjin

Re: [PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells

[Ralf Baechle]

On Sat, Jan 23, 2010 at 07:56:16PM +0800, Wu Zhangjin wrote:
> From: Wu Zhangjin <wuzhangjin@gmail.com>
> Date:   Sat, 23 Jan 2010 19:56:16 +0800
> To: Ralf Baechle <ralf@linux-mips.org>
> Cc: Alexander Clouter <alex@digriz.org.uk>, linux-mips@linux-mips.org
> Subject: Re: [PATCHv2] MIPS: fix vmlinuz build for 32bit-only math shells
> Content-Type: text/plain; charset="UTF-8"
> 
> On Fri, 2010-01-22 at 15:52 +0100, Ralf Baechle wrote:
> > On Wed, Jan 20, 2010 at 08:50:07PM +0000, Alexander Clouter wrote:
> > 
> > > Counter to the documentation for the dash shell, it seems that on my
> > > x86_64 filth under Debian only does 32bit math.  As I have configured my
> > 
> > POSIX apparently specifies at least "long" type arithmetic for shells, so
> > if your dash indeed is a 64-bit binary it's in violation of POSIX.  What
> > does
> > 
> >   file $(which $SHELL)
> > 
> > say?
> > 
> > The dash binary on my Fedora 12 i386 seems to perform 64-bit arithmetic.
> > 
> 
> Hi, Ralf
> 
> on my yeeloong laptop, with dash(0.5.5.1-3) in o32 ABI, it also can only
> execute 32-bit numbers, but on my thinkpad SL400(i686, dash version is
> 0.5.5.1-2), it works well with 64-bit arithmetic.
> 
> So, it means dash not always works normally, perhaps there is a bug
> there, or the bug only exists on MIPS machines?

Well, I was wondering if the dash being used by Alexander is simply
defect.  However in the end that doesn't matter; we try to restrict
the build environment to just a standard POSIX environment - or at least
as close as possible and that means we can only expect $((<expression))
to perform 32-bit arithmetic.

I've applied the patch for now but this is ugly.  I was even considering
if a small host C program that does the math is the lesser evil.

That said, applied.  Thanks folks!

  Ralf