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From: Michael Ellerman <mpe@ellerman.id.au>
To: Sven Schnelle <svens@stackframe.org>
Cc: kexec@lists.infradead.org, deller@gmx.de, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 5/7] kexec_elf: remove elf_addr_to_cpu macro
Date: Sat, 20 Jul 2019 00:06:21 +1000	[thread overview]
Message-ID: <87tvbi6rvm.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20190715072417.GA25659@t470p.stackframe.org>

Sven Schnelle <svens@stackframe.org> writes:
> Hi Michael,
>
> On Thu, Jul 11, 2019 at 09:08:51PM +1000, Michael Ellerman wrote:
>> Sven Schnelle <svens@stackframe.org> writes:
>> > On Wed, Jul 10, 2019 at 05:09:29PM +0200, Christophe Leroy wrote:
>> >> Le 10/07/2019 à 16:29, Sven Schnelle a écrit :
>> >> > It had only one definition, so just use the function directly.
>> >> 
>> >> It had only one definition because it was for ppc64 only.
>> >> But as far as I understand (at least from the name of the new file), you
>> >> want it to be generic, don't you ? Therefore I get on 32 bits it would be
>> >> elf32_to_cpu().
>> >
>> > That brings up the question whether we need those endianess conversions. I would
>> > assume that the ELF file has always the same endianess as the running kernel. So
>> > i think we could just drop them. What do you think?
>> 
>> We should be able to kexec from big to little endian or vice versa, so
>> they are necessary.
>
> I'll update the patch to check for a needed 32/64 bit conversion during runtime,
> so we can also kexec from 32 to 64 bit kernels and vice versa. Don't know
> whether that's possible on powerpc, but at least on parisc it is.

On some of the Freescale (NXP) machines that should actually be
possible, the hardware can run a 64 or 32-bit kernel, but I'm not sure
if anyone has actually tested kexec'ing from one to the other.

cheers

WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <mpe@ellerman.id.au>
To: Sven Schnelle <svens@stackframe.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>,
	kexec@lists.infradead.org, deller@gmx.de,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 5/7] kexec_elf: remove elf_addr_to_cpu macro
Date: Sat, 20 Jul 2019 00:06:21 +1000	[thread overview]
Message-ID: <87tvbi6rvm.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20190715072417.GA25659@t470p.stackframe.org>

Sven Schnelle <svens@stackframe.org> writes:
> Hi Michael,
>
> On Thu, Jul 11, 2019 at 09:08:51PM +1000, Michael Ellerman wrote:
>> Sven Schnelle <svens@stackframe.org> writes:
>> > On Wed, Jul 10, 2019 at 05:09:29PM +0200, Christophe Leroy wrote:
>> >> Le 10/07/2019 à 16:29, Sven Schnelle a écrit :
>> >> > It had only one definition, so just use the function directly.
>> >> 
>> >> It had only one definition because it was for ppc64 only.
>> >> But as far as I understand (at least from the name of the new file), you
>> >> want it to be generic, don't you ? Therefore I get on 32 bits it would be
>> >> elf32_to_cpu().
>> >
>> > That brings up the question whether we need those endianess conversions. I would
>> > assume that the ELF file has always the same endianess as the running kernel. So
>> > i think we could just drop them. What do you think?
>> 
>> We should be able to kexec from big to little endian or vice versa, so
>> they are necessary.
>
> I'll update the patch to check for a needed 32/64 bit conversion during runtime,
> so we can also kexec from 32 to 64 bit kernels and vice versa. Don't know
> whether that's possible on powerpc, but at least on parisc it is.

On some of the Freescale (NXP) machines that should actually be
possible, the hardware can run a 64 or 32-bit kernel, but I'm not sure
if anyone has actually tested kexec'ing from one to the other.

cheers

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kexec@lists.infradead.org
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  reply	other threads:[~2019-07-19 14:08 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-10 14:29 [PATCH v3 0/7] kexec: add generic support for elf kernel images Sven Schnelle
2019-07-10 14:29 ` Sven Schnelle
2019-07-10 14:29 ` [PATCH v3 1/7] kexec: add KEXEC_ELF Sven Schnelle
2019-07-10 14:29   ` Sven Schnelle
2019-07-10 14:29 ` [PATCH v3 2/7] kexec_elf: change order of elf_*_to_cpu() functions Sven Schnelle
2019-07-10 14:29   ` Sven Schnelle
2019-07-10 14:29 ` [PATCH v3 3/7] kexec_elf: remove parsing of section headers Sven Schnelle
2019-07-10 14:29   ` Sven Schnelle
2019-07-10 14:29 ` [PATCH v3 4/7] kexec_elf: remove PURGATORY_STACK_SIZE Sven Schnelle
2019-07-10 14:29   ` Sven Schnelle
2019-07-10 14:29 ` [PATCH v3 5/7] kexec_elf: remove elf_addr_to_cpu macro Sven Schnelle
2019-07-10 14:29   ` Sven Schnelle
2019-07-10 15:09   ` Christophe Leroy
2019-07-10 15:09     ` Christophe Leroy
2019-07-10 18:05     ` Sven Schnelle
2019-07-10 18:05       ` Sven Schnelle
2019-07-11 11:08       ` Michael Ellerman
2019-07-11 11:08         ` Michael Ellerman
2019-07-15  7:24         ` Sven Schnelle
2019-07-15  7:24           ` Sven Schnelle
2019-07-19 14:06           ` Michael Ellerman [this message]
2019-07-19 14:06             ` Michael Ellerman
2019-07-10 14:29 ` [PATCH v3 6/7] kexec_elf: remove Elf_Rel macro Sven Schnelle
2019-07-10 14:29   ` Sven Schnelle
2019-07-10 15:02   ` Christophe Leroy
2019-07-10 15:02     ` Christophe Leroy
2019-07-10 14:29 ` [PATCH v3 7/7] kexec_elf: remove unused variable in kexec_elf_load() Sven Schnelle
2019-07-10 14:29   ` Sven Schnelle
2019-07-10 14:55   ` Christophe Leroy
2019-07-10 14:55     ` Christophe Leroy

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