From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752520Ab0LPW4S (ORCPT ); Thu, 16 Dec 2010 17:56:18 -0500 Received: from g4t0014.houston.hp.com ([15.201.24.17]:28226 "EHLO g4t0014.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751608Ab0LPW4Q (ORCPT ); Thu, 16 Dec 2010 17:56:16 -0500 From: Bjorn Helgaas To: Linus Torvalds Subject: Re: [PATCH 6/9] resources: add arch hook for preventing allocation in reserved areas Date: Thu, 16 Dec 2010 15:56:06 -0700 User-Agent: KMail/1.13.2 (Linux/2.6.32-26-generic; KDE/4.4.2; x86_64; ; ) Cc: Jesse Barnes , Len Brown , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Adam Belay References: <20101216173614.8185.19462.stgit@bob.kio> <20101216173846.8185.82045.stgit@bob.kio> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201012161556.07868.bjorn.helgaas@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, December 16, 2010 03:03:21 pm Linus Torvalds wrote: > On Thu, Dec 16, 2010 at 9:38 AM, Bjorn Helgaas wrote: > > > > This adds arch_remove_reservations(), which an arch can implement if it > > needs to protect part of the address space from allocation. > > Oh, I just realized - we've had gcc (or maybe "as") bugs when the weak > symbol is in the same compilation unit as the caller, and some part of > the toolchain just ends up short-circuiting it (either gcc inlines it, > or maybe it was that as resolves it early). Making the "weak" part not > work, because it binds strongly. > > It may be that we don't support those gcc versions any more, but I > thought I'd bring the issue up. It's safer to put the weak functions > in some other file if possible. I'd be glad to repost and do that if necessary. Does anybody know for sure if it is? I did find these cases where we have a weak symbol definition in the same file as the caller, as well as another version elsewhere, so maybe those toolchains are indeed no longer supported? arch_disable_smp_support() defined and called in init/main.c (used for "nosmp" arg) also defined in arch/x86/kernel/apic/io_apic.c smp_setup_processor_id() defined and called in init/main.c also defined in arch/s390/kernel/smp.c also defined in arch/sparc/kernel/smp_64.c arch_enable_nonboot_cpus_begin() defined and called in kernel/cpu.c also defined in arch/x86/kernel/smpboot.c arch_irq_work_raise() defined and called in kernel/irq_work.c also defined in arch/sparc/kernel/pcr.c also defined in arch/x86/kernel/irq_work.c arch_jump_label_text_poke_early() defined and called in kernel/jump_label.c also defined in arch/sparc/kernel/jump_label.c also defined in arch/x86/kernel/jump_label.c arch_deref_entry_point() defined and called in kernel/kprobes.c also defined in arch/ia64/kernel/kprobes.c also defined in arch/powerpc/kernel/kprobes.c arch_scale_smt_power() defined and called in kernel/sched_fair.c also defined in arch/x86/kernel/cpu/sched.c memblock_nid_range() defined and called in mm/memblock.c also defined in arch/sparc/mm/init_64.c If this toolchain bug is still a problem, I would think all of the above would be defects, so my guess is that we don't have to worry about it any more. Bjorn