On Thu, Jul 31, 2008 at 09:21:52AM -0400, Vivek Goyal wrote: > On Thu, Jul 31, 2008 at 10:48:43AM +1000, Simon Horman wrote: > > On Wed, Jul 30, 2008 at 09:01:31AM -0400, Vivek Goyal wrote: > > > On Tue, Jul 29, 2008 at 06:12:38PM +1000, Simon Horman wrote: > > > > After recent changes setting elfcorehdr_addr to ELFCORE_ADDR_MAX > > > > will cause is_kdump_kernel() to return 0 when it should return 1. > > > > Instead use vmcore_unusable(), which has been added for this purpose. > > > > > > > > Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx> > > > > > > > > Index: linux-2.6/arch/ia64/kernel/setup.c > > > > =================================================================== > > > > --- linux-2.6.orig/arch/ia64/kernel/setup.c 2008-07-29 17:27:43.000000000 +1000 > > > > +++ linux-2.6/arch/ia64/kernel/setup.c 2008-07-29 17:50:50.000000000 +1000 > > > > @@ -502,11 +502,11 @@ int __init reserve_elfcorehdr(unsigned l > > > > * to work properly. > > > > */ > > > > > > > > - if (elfcorehdr_addr >= ELFCORE_ADDR_MAX) > > > > + if (!is_vmcore_usable()) > > > > return -EINVAL; > > > > > > > > if ((length = vmcore_find_descriptor_size(elfcorehdr_addr)) == 0) { > > > > - elfcorehdr_addr = ELFCORE_ADDR_MAX; > > > > + vmcore_unusable(); > > > > return -EINVAL; > > > > } > > > > > > > > > > Hi Simon, > > > > > > I had a question. I am not very sure what reserve_elfcorehdr is doing > > > but doing something similar to reserving some memory area where > > > elfcoreheaders are. > > > > Yes, that is my understanding of what it does. > > > > In x86 we never have to reserve that elf header area as we know that > booting kernel will never overwrite in that area. (Previous kernel has > modified the memory map in such a way so that elf header memory area > is not even part of memory range second kernel can use. > > Any idea, why do we need to reserve this area in IA64. > > > > I see that reserve_elfcorehdr is under CONFIG_PROC_VMCORE. Will it work > > > if CONFIG_PROC_VMCORE=n and somebody wants to use /dev/oldmem? > > > Or reserve_elfcorehdr should be under CONFIG_CRASH_DUMP? > > > > I'm not that familiar with /dev/oldmem, but as far as I can see, > > read_oldmem doesn't do anything with ELF headers, so reservation > > by vmcore_find_descriptor_size() should not be neccessary. > > > > /dev/oldmem does not directly touch elfcorehdr. But it indirectly does in > the sense that it is reading all the previous kernel's memory and dumping > it to disk. That would include elfcorehdrs also. > > Now if we need to do some kind of reservation for elf headers so that > fs/vmcore.c code can read it, then same should be true for /dev/oldmem > code also. Otherwise reserving elfcorehdr code should be redundant. > > That's why I raised the question that why do we need to reserve that area > in case of IA64. And if there is a genuine reason then probably that > reason will hold valid in case of /dev/oldmem also and we might have > to put is_vmcore_usable() definition also under CONFIG_CRASH_DUMP. Hi Vivek, yes, I do think that the problem is a bit deeper than my original response. I'll investigate this further. -- Horms -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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