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Re: [PATCH v1] MIPS: fix vmlinuz build when only 32bit math shell

To: Wu Zhangjin <wuzhangjin@gmail.com>
Subject: Re: [PATCH v1] MIPS: fix vmlinuz build when only 32bit math shell is available
From: Alexander Clouter <alex@digriz.org.uk>
Date: Tue, 19 Jan 2010 09:55:57 +0000
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
In-reply-to: <42fa29d2007a40a31a0bb8fbf1091e11eb9b5ac2.1263893871.git.wuzhangjin@gmail.com>
Organization: diGriz
References: <42fa29d2007a40a31a0bb8fbf1091e11eb9b5ac2.1263893871.git.wuzhangjin@gmail.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.18 (2008-05-17)
Hi,

* Wu Zhangjin <wuzhangjin@gmail.com> [2010-01-19 17:43:09+0800]:
> 
> Does this revision work for you?
>
> Changes from v0:
> 
>       - Revert the '-n "$(VMLINUX_SIZE)"' to avoid the error of "make clean"
>       - Consider more situations of the VMLINUX_LOAD_ADDRESS
> 
> [snipped]
>
> So, we can split the original 64bit string to two parts, and only
> calculate the low 32bit part, which is big enough(about 4095 M) for a
> normal linux kernel image file, now, we calculate the
> VMLINUZ_LOAD_ADDRESS like this:
>
As a passing query, why do we have the high 32bit (0xffffffff....) spiel 
if later we can just make VMLINU[XZ]_LOAD_ADDRESS the low half?  I see 
the output of 'nm' shows:
----
alex@berk:/usr/src/wag54g/linux$ nm vmlinux | head -n1
941019e4 t .ex0
alex@berk:/usr/src/wag54g/linux$ nm vmlinuz | head -n1
944abb50 B .heap
----

However I am guessing it's some 64bit CPU requirement as my x86_64 
kernel seems to have 0xffffffff....  Which raises the question, why is 
AR7 not just using VMLINUX_LOAD_ADDRESS=0x94100000?

> 1. Append "the high 32bit of VMLINUX_LOAD_ADDRESS" as the prefix if it
> exists.
> 
> 2. Get the sum of "the low 32bit of VMLINUX_LOAD_ADDRESS + VMLINUX_SIZE"
> with printf "%08x" (08 herein is used to prefix the result with 0...)
> 
> The corresponding shell script is:
> 
>   A=$VMLINUX_LOAD_ADDRESS;
>   # Append "the high 32bit of VMLINUX_LOAD_ADDRESS" as the prefix if it 
> exists.
>   [ "${A:0:10}" != "${A}" ] && echo -n ${A:2:8};
>   # Get the sum of "the low 32bit of VMLINUX_LOAD_ADDRESS + VMLINUX_SIZE"
>   printf "%08x" $(($VMLINUX_SIZE + 0x${A:(-8)}))
> 
Eugh, bash-ism's...
----
alex@berk:/usr/src/wag54g/linux$ bash -c 'A=1234567890; echo ${A:0:5}'
12345
alex@berk:/usr/src/wag54g/linux$ dash -c 'A=1234567890; echo ${A:0:5}'
dash: Bad substitution
----

Your 'punishment', use Plan9 for a period of no less than a week! :)

You have to use the pattern matching approach I used in my original 
patch, that's portable.  Look at 'man 1 dash' and search for 'substr' 
for more details.

Cheers

-- 
Alexander Clouter
.sigmonster says: I'm not prejudiced, I hate everyone equally.

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