From: Vivek Goyal <vgoyal@redhat.com> To: Michael Holzheu <holzheu@linux.vnet.ibm.com> Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>, Jan Willeke <willeke@de.ibm.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, linux-kernel@vger.kernel.org, kexec@lists.infradead.org Subject: Re: [PATCH v5 1/5] vmcore: Introduce ELF header in new memory feature Date: Mon, 1 Jul 2013 13:37:27 -0400 [thread overview] Message-ID: <20130701173727.GD9840@redhat.com> (raw) In-Reply-To: <20130628101552.68aab404@holzheu> On Fri, Jun 28, 2013 at 10:15:52AM +0200, Michael Holzheu wrote: > On Thu, 27 Jun 2013 16:23:34 -0400 > Vivek Goyal <vgoyal@redhat.com> wrote: > > > On Thu, Jun 27, 2013 at 03:32:02PM -0400, Vivek Goyal wrote: > > > On Fri, Jun 21, 2013 at 04:17:03PM +0200, Michael Holzheu wrote: > > > > On Fri, 14 Jun 2013 14:54:02 -0400 > > > > Vivek Goyal <vgoyal@redhat.com> wrote: > > [snip] > > > Thinking more about it, I think let us cleanup with this little ugly > > bit too so that future changes become easy. > > > > Current convention is that elfcorehdr_addr and elfcorehdr_size are > > already set by arch code by the time vmcore.c starts reading it. Can't > > s390 allocate elf headers in early boot code and elfcorehdr_addr? Then > > we don't have to call elfcorehdr_alloc(). > > > > And once we are done with reading headers, we can call elfcorehdr_free() > > and s390 could free memory and set elfcorehdr_addr to ELFCORE_ADDR_ERR > > and elfcorehdr_size=0. That would signify that one can not try to read > > elf headers now and it must have been freed. > > > > is_kdump_kernel() will continue to work as elfcorehdr_addr is > > ELFCORE_ADDR_ERR. And that will mean that either elfcorehdr were not > > readable/usable to begin with or they have been freed now. > > Hello Vivek, > > We would like to keep the alloc/free symmetry as you have suggested in a > previous mail. This also has the advantage that we do not have to rely > on the ordering of init calls. > > Wouldn't it be sufficient to just set elfcorehdr_addr to ELFCORE_ADDR_ERR > after elfcorehdr_free() and remove the comment? > Hi Michael, This has only one problem and that is what's the initialization semantics of elfcorehdr_addr. So far we expected it to be initialized very early in boot process and once this is set, any component in the system could figure out if it is kdump kernel (is_kdump_kernel()) and do kdump specific things. But if we move initialization of this variable little late, then it might be a problem for early users of is_kdump_kernel(). Though right now I don't see drivers making use of it and only arch specific early boot up code seems to have it. So either we can stick to existing semantics of initializing headers early or we could create a separate variable for is_kdump_kernel() which is set in early boot and then one can delay initialization of elfcorehdr_addr() in vmcore_init(). Given the fact that I don't see any users of is_kdump_kernel() in arch independent directory, and I am assuming that you will tackle all early users of is_kdump_kernel() in s390, I will be fine even with your patch below. Thanks Vivek > So the code would look like the following: > > static int __init vmcore_init(void) > { > int rc = 0; > > /* Allow architectures to allocate ELF header in 2nd kernel */ > rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size); > if (rc) > return rc; > /* > * If elfcorehdr= has been passed in cmdline or created in 2nd kernel, > * then capture the dump. > */ > if (!(is_vmcore_usable())) > return rc; > rc = parse_crash_elf_headers(); > if (rc) { > pr_warn("Kdump: vmcore not initialized\n"); > return rc; > } > elfcorehdr_free(elfcorehdr_addr); > elfcorehdr_addr = ELFCORE_ADDR_ERR; > > proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations); > if (proc_vmcore) > proc_vmcore->size = vmcore_size; > return 0; > } > > This looks clean for me. > > What do you think? > > Best Regards, > Michael
WARNING: multiple messages have this Message-ID (diff)
From: Vivek Goyal <vgoyal@redhat.com> To: Michael Holzheu <holzheu@linux.vnet.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>, kexec@lists.infradead.org, Jan Willeke <willeke@de.ibm.com>, linux-kernel@vger.kernel.org, HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>, Martin Schwidefsky <schwidefsky@de.ibm.com> Subject: Re: [PATCH v5 1/5] vmcore: Introduce ELF header in new memory feature Date: Mon, 1 Jul 2013 13:37:27 -0400 [thread overview] Message-ID: <20130701173727.GD9840@redhat.com> (raw) In-Reply-To: <20130628101552.68aab404@holzheu> On Fri, Jun 28, 2013 at 10:15:52AM +0200, Michael Holzheu wrote: > On Thu, 27 Jun 2013 16:23:34 -0400 > Vivek Goyal <vgoyal@redhat.com> wrote: > > > On Thu, Jun 27, 2013 at 03:32:02PM -0400, Vivek Goyal wrote: > > > On Fri, Jun 21, 2013 at 04:17:03PM +0200, Michael Holzheu wrote: > > > > On Fri, 14 Jun 2013 14:54:02 -0400 > > > > Vivek Goyal <vgoyal@redhat.com> wrote: > > [snip] > > > Thinking more about it, I think let us cleanup with this little ugly > > bit too so that future changes become easy. > > > > Current convention is that elfcorehdr_addr and elfcorehdr_size are > > already set by arch code by the time vmcore.c starts reading it. Can't > > s390 allocate elf headers in early boot code and elfcorehdr_addr? Then > > we don't have to call elfcorehdr_alloc(). > > > > And once we are done with reading headers, we can call elfcorehdr_free() > > and s390 could free memory and set elfcorehdr_addr to ELFCORE_ADDR_ERR > > and elfcorehdr_size=0. That would signify that one can not try to read > > elf headers now and it must have been freed. > > > > is_kdump_kernel() will continue to work as elfcorehdr_addr is > > ELFCORE_ADDR_ERR. And that will mean that either elfcorehdr were not > > readable/usable to begin with or they have been freed now. > > Hello Vivek, > > We would like to keep the alloc/free symmetry as you have suggested in a > previous mail. This also has the advantage that we do not have to rely > on the ordering of init calls. > > Wouldn't it be sufficient to just set elfcorehdr_addr to ELFCORE_ADDR_ERR > after elfcorehdr_free() and remove the comment? > Hi Michael, This has only one problem and that is what's the initialization semantics of elfcorehdr_addr. So far we expected it to be initialized very early in boot process and once this is set, any component in the system could figure out if it is kdump kernel (is_kdump_kernel()) and do kdump specific things. But if we move initialization of this variable little late, then it might be a problem for early users of is_kdump_kernel(). Though right now I don't see drivers making use of it and only arch specific early boot up code seems to have it. So either we can stick to existing semantics of initializing headers early or we could create a separate variable for is_kdump_kernel() which is set in early boot and then one can delay initialization of elfcorehdr_addr() in vmcore_init(). Given the fact that I don't see any users of is_kdump_kernel() in arch independent directory, and I am assuming that you will tackle all early users of is_kdump_kernel() in s390, I will be fine even with your patch below. Thanks Vivek > So the code would look like the following: > > static int __init vmcore_init(void) > { > int rc = 0; > > /* Allow architectures to allocate ELF header in 2nd kernel */ > rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size); > if (rc) > return rc; > /* > * If elfcorehdr= has been passed in cmdline or created in 2nd kernel, > * then capture the dump. > */ > if (!(is_vmcore_usable())) > return rc; > rc = parse_crash_elf_headers(); > if (rc) { > pr_warn("Kdump: vmcore not initialized\n"); > return rc; > } > elfcorehdr_free(elfcorehdr_addr); > elfcorehdr_addr = ELFCORE_ADDR_ERR; > > proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations); > if (proc_vmcore) > proc_vmcore->size = vmcore_size; > return 0; > } > > This looks clean for me. > > What do you think? > > Best Regards, > Michael _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2013-07-01 17:37 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-06-07 16:55 [PATCH v5 0/5] kdump: Allow ELF header creation in new kernel Michael Holzheu 2013-06-07 16:55 ` Michael Holzheu 2013-06-07 16:55 ` [PATCH v5 1/5] vmcore: Introduce ELF header in new memory feature Michael Holzheu 2013-06-07 16:55 ` Michael Holzheu 2013-06-10 13:35 ` HATAYAMA Daisuke 2013-06-10 13:35 ` HATAYAMA Daisuke 2013-06-10 13:53 ` Michael Holzheu 2013-06-10 13:53 ` Michael Holzheu 2013-06-14 18:54 ` Vivek Goyal 2013-06-14 18:54 ` Vivek Goyal 2013-06-21 14:17 ` Michael Holzheu 2013-06-21 14:17 ` Michael Holzheu 2013-06-27 19:32 ` Vivek Goyal 2013-06-27 19:32 ` Vivek Goyal 2013-06-27 20:10 ` Cliff Wickman 2013-06-27 20:10 ` Cliff Wickman 2013-06-27 20:23 ` Vivek Goyal 2013-06-27 20:23 ` Vivek Goyal 2013-06-28 8:15 ` Michael Holzheu 2013-06-28 8:15 ` Michael Holzheu 2013-07-01 17:37 ` Vivek Goyal [this message] 2013-07-01 17:37 ` Vivek Goyal 2013-07-01 18:29 ` Michael Holzheu 2013-07-01 18:29 ` Michael Holzheu 2013-06-07 16:55 ` [PATCH v5 2/5] s390/vmcore: Use " Michael Holzheu 2013-06-07 16:55 ` Michael Holzheu 2013-06-10 13:36 ` HATAYAMA Daisuke 2013-06-10 13:36 ` HATAYAMA Daisuke 2013-06-10 13:48 ` Michael Holzheu 2013-06-10 13:48 ` Michael Holzheu 2013-06-14 19:16 ` Vivek Goyal 2013-06-14 19:16 ` Vivek Goyal 2013-06-07 16:55 ` [PATCH v5 3/5] vmcore: Introduce remap_oldmem_pfn_range() Michael Holzheu 2013-06-07 16:55 ` Michael Holzheu [not found] ` <CAJGZr0+_W0dp2f9VtVAiUT2fqiwe91gHXd9zYzfMMzBZSZogww@mail.gmail.com> 2013-06-10 8:00 ` Michael Holzheu 2013-06-10 8:00 ` Michael Holzheu 2013-06-10 13:40 ` HATAYAMA Daisuke 2013-06-10 13:40 ` HATAYAMA Daisuke 2013-06-10 14:03 ` Michael Holzheu 2013-06-10 14:03 ` Michael Holzheu 2013-06-10 15:37 ` Michael Holzheu 2013-06-10 15:37 ` Michael Holzheu 2013-06-11 12:42 ` HATAYAMA Daisuke 2013-06-11 12:42 ` HATAYAMA Daisuke 2013-06-12 9:13 ` Michael Holzheu 2013-06-12 9:13 ` Michael Holzheu 2013-06-13 1:32 ` HATAYAMA Daisuke 2013-06-13 1:32 ` HATAYAMA Daisuke 2013-06-13 8:54 ` Michael Holzheu 2013-06-13 8:54 ` Michael Holzheu 2013-06-13 4:00 ` HATAYAMA Daisuke 2013-06-13 4:00 ` HATAYAMA Daisuke 2013-06-11 13:20 ` HATAYAMA Daisuke 2013-06-11 13:20 ` HATAYAMA Daisuke 2013-06-07 16:56 ` [PATCH v5 4/5] s390/vmcore: Implement remap_oldmem_pfn_range for s390 Michael Holzheu 2013-06-07 16:56 ` Michael Holzheu 2013-06-14 20:08 ` Vivek Goyal 2013-06-14 20:08 ` Vivek Goyal 2013-06-07 16:56 ` [PATCH v5 5/5] s390/vmcore: Use vmcore for zfcpdump Michael Holzheu 2013-06-07 16:56 ` Michael Holzheu 2013-06-11 23:47 ` HATAYAMA Daisuke 2013-06-11 23:47 ` HATAYAMA Daisuke 2013-06-12 9:14 ` Michael Holzheu 2013-06-12 9:14 ` Michael Holzheu 2013-06-14 18:54 ` [PATCH v5 0/5] kdump: Allow ELF header creation in new kernel Vivek Goyal 2013-06-14 18:54 ` Vivek Goyal 2013-06-21 13:39 ` Michael Holzheu 2013-06-21 13:39 ` Michael Holzheu
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20130701173727.GD9840@redhat.com \ --to=vgoyal@redhat.com \ --cc=d.hatayama@jp.fujitsu.com \ --cc=heiko.carstens@de.ibm.com \ --cc=holzheu@linux.vnet.ibm.com \ --cc=kexec@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=schwidefsky@de.ibm.com \ --cc=willeke@de.ibm.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.