From: Anton Blanchard <anton@samba•org>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linuxppc-dev@lists•ozlabs.org, paulus@samba•org, amodra@gmail•com
Subject: Re: [PATCH 1/3] powerpc: Relocate prom_init.c on 64bit
Date: Wed, 5 Dec 2012 11:07:23 +1100 [thread overview]
Message-ID: <20121205110723.68839261@kryten> (raw)
In-Reply-To: <1353993743.2179.28.camel@pasglop>
Hi Ben,
> My only potential objection was that it might have been cleaner to
> actually build prom_init.c as a separate binary alltogether and piggy
> back it...
Yeah, I went through a number of options before settling on this one.
Move prom_init.c into arch/powerpc/boot
Pros:
- 32 bit environment fits well with 32 bit OF interface
- Clear separation enforced between prom_init.c and rest of kernel
- Can build boot wrapper -mrelocatable, similar to ppc32 kernel
Cons:
- tools that assume we can boot a vmlinux will break.
- distro bootloader tools
- provisioning and test environments
- profiling and debugging tools that currently use a vmlinux will break
- oprofile, perf
- Places more pressure on already fragile early memory map
- have to uncompress the zImage somewhere in the RMO
- prom_init.c needs to pull in quite a lot of kernel headers
- seemed difficult to force them to build 32 bit
- Increased simulator boot times due to uncompress stage
Build prom_init.c 32 bit and attach the vmlinux as a binary blob.
This means a vmlinux will be bootable, but profiling tools still wont
work.
Build prom_init.c 32 bit, tack it onto the end of the vmlinux and
add a trampoline at the start of the vmlinux.
This means a vmlinux will be bootable and profiling tools will work
against it. Even so it feels gross to me.
Anton
next prev parent reply other threads:[~2012-12-05 0:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-27 3:39 [PATCH 1/3] powerpc: Relocate prom_init.c on 64bit Anton Blanchard
2012-11-27 3:40 ` [PATCH 2/3] powerpc: Remove RELOC() macro Anton Blanchard
2012-11-27 3:41 ` [PATCH 3/3] powerpc: Build kernel with -mcmodel=medium Anton Blanchard
2012-11-27 5:22 ` [PATCH 1/3] powerpc: Relocate prom_init.c on 64bit Benjamin Herrenschmidt
2012-12-05 0:07 ` Anton Blanchard [this message]
2012-12-05 7:20 ` Benjamin Herrenschmidt
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