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

[Wu Zhangjin <wuzhangjin@gmail.com>]

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