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Date:   Mon, 06 Apr 2020 19:10:58 +0800
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Subject: Re: [PATCH] MIPS: malta: Set load address for 32bit kernel correctly
To:     YunQiang Su <wzssyqa@gmail.com>,
        "Maciej W. Rozycki" <macro@linux-mips.org>
CC:     linux-mips <linux-mips@vger.kernel.org>,
        Fangrui Song <maskray@google.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        LKML <linux-kernel@vger.kernel.org>
From:   Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-ID: <079F408B-9C44-4317-8DD3-7A1896564960@flygoat.com>
Sender: linux-kernel-owner@vger.kernel.org
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=E4=BA=8E 2020=E5=B9=B44=E6=9C=886=E6=97=A5 GMT+08:00 =E4=B8=8B=E5=8D=886:=
57:18, YunQiang Su <wzssyqa@gmail=2Ecom> =E5=86=99=E5=88=B0:
>Maciej W=2E Rozycki <macro@linux-mips=2Eorg> =E4=BA=8E2020=E5=B9=B44=E6=
=9C=886=E6=97=A5=E5=91=A8=E4=B8=80 =E4=B8=8A=E5=8D=881:23=E5=86=99=E9=81=93=
=EF=BC=9A
>>
>> On Mon, 6 Apr 2020, Jiaxun Yang wrote:
>>
>> > > Given the description above I think it should be done uniformly
>and
>> > >automatically across all platforms by trimming the address
>supplied
>> > >with
>> > >$(load-y) to low 8 digits in a single place, that is at the place
>where
>> > >
>> > >the variable is consumed=2E  This will reduce clutter across
>Makefile
>> > >fragments, avoid inconsistencies and extra work to handle
>individual
>> > >platforms as the problem is triggered over and over again, and
>limit
>> > >the
>> > >risk of mistakes=2E
>> >
>> > I was intended to do like this but failed to find a proper way=2E
>> >
>> > Makefile isn't designed for any kind of calculation=2E
>> > And shell variables are 64-bit signed so it can't hold such a huge
>variable=2E
>> >
>> > Just wish somebody can give me a way to do like:
>> >
>> > ifndef CONFIG_64BIT
>> > load-y =3D $(load-y) & 0xffffffff
>> > endif
>>
>>  Use the usual shell tools like `sed', `cut', `awk', or whatever we
>use in
>
>perl may be the easiest to use tool here=2E
>
>ifndef CONFIG_64BIT
>  load-y :=3D $(shell $(PERL) -e 'print $(load-y) & 0xffffffff')
>endif
>
>Note that it is `:=3D' instead of '=3D'=2E

It seems like perl is not one of kernel's build dependencies=2E[1]
I'm comsidering a alternative solution,
write a small hostprog in C to deal with that=2E

Thanks=2E

[1]: https://www=2Ekernel=2Eorg/doc/html/v5=2E6/process/changes=2Ehtml


>
>> the kernel build already for other purposes=2E  There's no need to do
>any
>> actual calculation here to extract the last 8 characters (and the
>leading
>> `0x' prefix)=2E  At worst you can write a small C program, compile it
>with
>> the build system compiler and run, as we already do for some stuff=2E
>>
>>   Maciej

--=20
Jiaxun Yang