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From:   YunQiang Su <wzssyqa@gmail.com>
Date:   Mon, 6 Apr 2020 18:57:18 +0800
Message-ID: <CAKcpw6U=VW+h4sU1fzrsqXU9z-zVfcFsENKHgAD4paqtndip2w@mail.gmail.com>
Subject: Re: [PATCH] MIPS: malta: Set load address for 32bit kernel correctly
To:     "Maciej W. Rozycki" <macro@linux-mips.org>
Cc:     Jiaxun Yang <jiaxun.yang@flygoat.com>,
        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>
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Maciej W. Rozycki <macro@linux-mips.org> =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 wher=
e
> > >
> > >the variable is consumed.  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.
> >
> > I was intended to do like this but failed to find a proper way.
> >
> > Makefile isn't designed for any kind of calculation.
> > And shell variables are 64-bit signed so it can't hold such a huge vari=
able.
> >
> > 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 i=
n

perl may be the easiest to use tool here.

ifndef CONFIG_64BIT
  load-y :=3D $(shell $(PERL) -e 'print $(load-y) & 0xffffffff')
endif

Note that it is `:=3D' instead of '=3D'.

> the kernel build already for other purposes.  There's no need to do any
> actual calculation here to extract the last 8 characters (and the leading
> `0x' prefix).  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.
>
>   Maciej


--=20
YunQiang Su