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From:   Alexandre Ghiti <alexandre.ghiti@canonical.com>
Date:   Wed, 27 Oct 2021 10:58:44 +0200
Message-ID: <CA+zEjCuRuKtZAhkS_RFyby6UhLvYmg=4BdnXEwUdaCdtbB7ZAA@mail.gmail.com>
Subject: Re: [PATCH] RISC-V: Make CONFIG_RELOCATABLE user selectable
To:     Andreas Schwab <schwab@linux-m68k.org>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>, alex@ghiti.fr,
        Paul Walmsley <paul.walmsley@sifive.com>,
        aou@eecs.berkeley.edu, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, kernel-team@android.com,
        Palmer Dabbelt <palmerdabbelt@google.com>
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On Wed, Oct 27, 2021 at 10:03 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Okt 26 2021, Palmer Dabbelt wrote:
>
> > +config RELOCATABLE
> > +     bool "Build a relocatable kernel"
> > +     depends on MMU && 64BIT && !XIP_KERNEL
> > +     help
> > +          This builds a kernel as a Position Independent Executable (PIE),
> > +          which retains all relocation metadata required to relocate the
> > +          kernel binary at runtime to a different virtual address than the
> > +          address it was linked at.
> > +          Since RISCV uses the RELA relocation format, this requires a
> > +          relocation pass at runtime even if the kernel is loaded at the
> > +          same address it was linked at.
>
> When in doubt, do what?

Then do not enable. it will be automatically selected by other configs
like KASLR, but otherwise you should not say yes since you'll just
have an identical slightly slower kernel.

But I imagine you mean adding a default value for this config? That
sounds right and it should be "default n".

Alex

>
> Andreas.
>
> --
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
> "And now for something completely different."
>
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