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From: Alex Ghiti <alex@ghiti.fr>
To: Jerome Forissier <jerome@forissier.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Anup Patel <Anup.Patel@wdc.com>,
	Atish Patra <Atish.Patra@wdc.com>, Zong Li <zong.li@sifive.com>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-riscv@lists.infradead.org
Cc: Anup Patel <anup@brainfault.org>
Subject: Re: [PATCH v5 2/4] riscv: Introduce CONFIG_RELOCATABLE
Date: Thu, 11 Jun 2020 15:43:56 -0400	[thread overview]
Message-ID: <43ef1623-2186-aa07-cfa5-d618aa4f09c0@ghiti.fr> (raw)
In-Reply-To: <b588dd9e-dff8-3458-0c7d-149e3990bca7@forissier.org>

Hi Jerome,

Le 6/10/20 à 10:10 AM, Jerome Forissier a écrit :
> On 6/7/20 9:59 AM, Alexandre Ghiti wrote:
> [...]
>
>> +config RELOCATABLE
>> +	bool
>> +	depends on MMU
>> +	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.
> Is this true? I thought that the GNU linker would write the "proper"
> values by default, contrary to the LLVM linker (ld.lld) which would need
> a special flag: --apply-dynamic-relocs (by default the relocated places
> are set to zero). At least, it is my experience with Aarch64 on a
> different project. So, sorry if I'm talking nonsense here -- I have not
> looked at the details.
>
>

It seems that you're right, at least for aarch64 since they specifically 
specify the --no-apply-dynamic-relocs option. I retried to boot without 
relocating at runtime, and it fails on riscv. Can this be arch specific ?

Thanks,

Alex


  reply	other threads:[~2020-06-11 19:44 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-07  7:59 [PATCH v5 0/4] vmalloc kernel mapping and relocatable kernel Alexandre Ghiti
2020-06-07  7:59 ` [PATCH v5 1/4] riscv: Move kernel mapping to vmalloc zone Alexandre Ghiti
2020-06-11 21:34   ` Atish Patra
2020-06-11 21:34     ` Atish Patra
2020-06-11 21:34     ` Atish Patra
2020-06-12 12:30     ` Alex Ghiti
2020-06-12 12:30       ` Alex Ghiti
2020-06-12 12:30       ` Alex Ghiti
2020-07-09  5:05   ` Palmer Dabbelt
2020-07-09  5:05     ` Palmer Dabbelt
2020-07-09  5:05     ` Palmer Dabbelt
2020-07-09  8:15     ` Zong Li
2020-07-09  8:15       ` Zong Li
2020-07-09  8:15       ` Zong Li
2020-07-09 11:11     ` Alex Ghiti
2020-07-09 11:11       ` Alex Ghiti
2020-07-09 11:11       ` Alex Ghiti
2020-07-21 18:36       ` Alex Ghiti
2020-07-21 18:36         ` Alex Ghiti
2020-07-21 18:36         ` Alex Ghiti
2020-07-21 19:05         ` Palmer Dabbelt
2020-07-21 19:05           ` Palmer Dabbelt
2020-07-21 19:05           ` Palmer Dabbelt
2020-07-21 23:12           ` Benjamin Herrenschmidt
2020-07-21 23:12             ` Benjamin Herrenschmidt
2020-07-21 23:12             ` Benjamin Herrenschmidt
2020-07-21 23:48             ` Palmer Dabbelt
2020-07-21 23:48               ` Palmer Dabbelt
2020-07-21 23:48               ` Palmer Dabbelt
2020-07-22  2:21               ` Benjamin Herrenschmidt
2020-07-22  2:21                 ` Benjamin Herrenschmidt
2020-07-22  2:21                 ` Benjamin Herrenschmidt
2020-07-22  4:50                 ` Michael Ellerman
2020-07-22  4:50                   ` Michael Ellerman
2020-07-22  4:50                   ` Michael Ellerman
2020-07-22  5:46                   ` Palmer Dabbelt
2020-07-22  5:46                     ` Palmer Dabbelt
2020-07-22  5:46                     ` Palmer Dabbelt
2020-07-22  9:43           ` Arnd Bergmann
2020-07-22  9:43             ` Arnd Bergmann
2020-07-22  9:43             ` Arnd Bergmann
2020-07-22  9:43             ` Arnd Bergmann
2020-07-22 19:52             ` Palmer Dabbelt
2020-07-22 19:52               ` Palmer Dabbelt
2020-07-22 19:52               ` Palmer Dabbelt
2020-07-22 20:22               ` Arnd Bergmann
2020-07-22 20:22                 ` Arnd Bergmann
2020-07-22 20:22                 ` Arnd Bergmann
2020-07-22 20:22                 ` Arnd Bergmann
2020-07-22 21:05                 ` Atish Patra
2020-07-22 21:05                   ` Atish Patra
2020-07-22 21:05                   ` Atish Patra
2020-07-22 21:05                   ` Atish Patra
2020-07-24  7:20                   ` Arnd Bergmann
2020-07-24  7:20                     ` Arnd Bergmann
2020-07-24  7:20                     ` Arnd Bergmann
2020-07-24  7:20                     ` Arnd Bergmann
2020-07-23  5:32           ` Alex Ghiti
2020-07-23  5:32             ` Alex Ghiti
2020-07-23  5:32             ` Alex Ghiti
2020-07-21 23:11         ` Benjamin Herrenschmidt
2020-07-21 23:11           ` Benjamin Herrenschmidt
2020-07-21 23:11           ` Benjamin Herrenschmidt
2020-07-21 23:36           ` Palmer Dabbelt
2020-07-21 23:36             ` Palmer Dabbelt
2020-07-21 23:36             ` Palmer Dabbelt
2020-07-23  5:36             ` Alex Ghiti
2020-07-23  5:36               ` Alex Ghiti
2020-07-23  5:36               ` Alex Ghiti
2020-07-23  5:21           ` Alex Ghiti
2020-07-23  5:21             ` Alex Ghiti
2020-07-23  5:21             ` Alex Ghiti
2020-07-23 22:33             ` Benjamin Herrenschmidt
2020-07-23 22:33               ` Benjamin Herrenschmidt
2020-07-23 22:33               ` Benjamin Herrenschmidt
2020-07-24  8:14               ` Arnd Bergmann
2020-07-24  8:14                 ` Arnd Bergmann
2020-07-24  8:14                 ` Arnd Bergmann
2020-07-24  8:14                 ` Arnd Bergmann
2020-06-07  7:59 ` [PATCH v5 2/4] riscv: Introduce CONFIG_RELOCATABLE Alexandre Ghiti
2020-06-07  7:59   ` Alexandre Ghiti
2020-06-10 14:10   ` Jerome Forissier
2020-06-11 19:43     ` Alex Ghiti [this message]
2020-06-07  7:59 ` [PATCH v5 3/4] powerpc: Move script to check relocations at compile time in scripts/ Alexandre Ghiti
2020-06-07  7:59   ` Alexandre Ghiti
2020-06-07  7:59 ` [PATCH v5 4/4] riscv: Check relocations at compile time Alexandre Ghiti
2020-06-07  7:59   ` Alexandre Ghiti
2020-07-08  4:21 ` [PATCH v5 0/4] vmalloc kernel mapping and relocatable kernel Alex Ghiti
2020-07-08  4:21   ` Alex Ghiti

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