From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from kirsty.vergenet.net ([202.4.237.240]) by canuck.infradead.org with esmtp (Exim 4.72 #1 (Red Hat Linux)) id 1P9StW-0002cM-Hw for kexec@lists.infradead.org; Sat, 23 Oct 2010 01:27:39 +0000 Date: Fri, 22 Oct 2010 10:54:12 +0200 From: Simon Horman Subject: Re: [PATCH,RFC] - make /proc/vmcore accesable on x86_64 Message-ID: <20101022085412.GA8267@verge.net.au> References: <20101019150630.GA1870@jolsa.brq.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20101019150630.GA1870@jolsa.brq.redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Jiri Olsa Cc: kexec@lists.infradead.org On Tue, Oct 19, 2010 at 05:06:30PM +0200, Jiri Olsa wrote: > hi, > > I was playing around with preserve context feature on x86_64 > and was not able to get the /proc/vmcore in the kexec-ed > kernel until I aplied attached patch. > > I'm not at all sure this is right fix ;) but it seems > that /proc/vmcore is not loaded since the machine field in the > elf header is wrong. > > > If the x86_64 arch returns 0 (KEXEC_ARCH_DEFAULT) then following > condition in load_crashdump_segments function will fill 386 as the > machine for the vmcore elf header.. > > ... > > if ((info->kexec_flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_X86_64) > { > elf_info.machine = EM_X86_64; > } else { > elf_info.machine = EM_386; > elf_info.lowmem_limit = X86_MAXMEM; > elf_info.get_note_info = get_crash_notes; > } > ... > > ending with kexec-ed kernel failing check for the machine, > and disabling vmcore interface... > > > I'm guessing that the reason is the load_crashdump_segments function > being shared among 32 and 64 bits.. but again, not sure ;) > > > My goal is to share data within the host and kexec-ed kernel, > so I'd like to use the /proc/vmcore for that.. any other > ideas are welcome :) This approach seems reasonable to me. I'll push it if a I don't hear any objections in the near future. > > > thanks, > jirka > --- > diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c > index 06e5ae9..40f989a 100644 > --- a/kexec/arch/i386/crashdump-x86.c > +++ b/kexec/arch/i386/crashdump-x86.c > @@ -691,6 +691,8 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline, > struct memory_range *mem_range, *memmap_p; > struct crash_elf_info elf_info; > > + memset(&elf_info, 0x0, sizeof(elf_info)); > + > /* Constant parts of the elf_info */ > elf_info.data = ELFDATA2LSB; > elf_info.backup_src_start = BACKUP_SRC_START; > diff --git a/kexec/arch/x86_64/kexec-x86_64.c b/kexec/arch/x86_64/kexec-x86_64.c > index 3092643..c34fd92 100644 > --- a/kexec/arch/x86_64/kexec-x86_64.c > +++ b/kexec/arch/x86_64/kexec-x86_64.c > @@ -134,10 +134,7 @@ int arch_process_options(int argc, char **argv) > } > > const struct arch_map_entry arches[] = { > - /* For compatibility with older patches > - * use KEXEC_ARCH_DEFAULT instead of KEXEC_ARCH_X86_64 here. > - */ > - { "x86_64", KEXEC_ARCH_DEFAULT }, > + { "x86_64", KEXEC_ARCH_X86_64 }, > { NULL, 0 }, > }; > > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec