linux-kernel - Re: 2.6.19-rc1: kexec broken on x86

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Date:	Fri, 06 Oct 2006 11:28:27 +0900
From:	Magnus Damm <magnus@...inux.co.jp>
To:	vgoyal@...ibm.com
Cc:	Magnus Damm <magnus.damm@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	fastboot@...ts.osdl.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Horms <horms@...ge.net.au>, Andi Kleen <ak@....de>,
	Ian.Campbell@...Source.com
Subject: Re: 2.6.19-rc1: kexec broken on x86_64

On Thu, 2006-10-05 at 12:33 -0400, Vivek Goyal wrote:
> On Thu, Oct 05, 2006 at 10:56:51PM +0900, Magnus Damm wrote:
> > Hi Vivek,
> > 
> > On 10/5/06, Vivek Goyal <vgoyal@...ibm.com> wrote:
> > >On Thu, Oct 05, 2006 at 07:28:35PM +0900, Magnus Damm wrote:
> > >> Kexec is broken on x86_64 under 2.6.19-rc1.
> > >>
> > >> Or rather - kexec works ok under 2.6.19-rc1, but something related to
> > >> the vmlinux format has probably changed and kexec-tools fails to load
> > >> a vmlinux from 2.6.19-rc1.
> > >>
> > >> Loading bzImage works as usual, but vmlinux does not load properly.
> > >>
> > >> The kexec binary fails with the following message:
> > >>
> > >> Overlapping memory segments at 0x351000
> > >> sort_segments failed
> > >> / #
> > >>
> > >
> > >Hi Magnus,
> > >
> > >Can you please post the readelf -l output of the vmlinux you are trying
> > >to load. That's will give some indication if the segments are really
> > >overlapping in vmlinux or is it some processing bug at kexec-tools part.
> > 
> > Elf file type is EXEC (Executable file)
> > Entry point 0x100100
> > There are 4 program headers, starting at offset 64
> > 
> > Program Headers:
> >  Type           Offset             VirtAddr           PhysAddr
> >                 FileSiz            MemSiz              Flags  Align
> >  LOAD           0x0000000000100000 0xffffffff80100000 0x0000000000100000
> >                 0x00000000001a4888 0x00000000001a4888  R E    100000
> >  LOAD           0x00000000002a5000 0xffffffff802a5000 0x00000000002a5000
> >                 0x000000000008e086 0x00000000000c1504  RWE    100000
> >  LOAD           0x0000000000400000 0xffffffffff600000 0x00000000002fd000
> >                 0x0000000000000c08 0x0000000000000c08  RWE    100000
> >  NOTE           0x0000000000000000 0x0000000000000000 0x0000000000000000
> >                 0x0000000000000000 0x0000000000000000  R      8
> > 
> > Section to Segment mapping:
> >  Segment Sections...
> >   00     .text __ex_table .rodata .pci_fixup __ksymtab __ksymtab_gpl
> > __ksymtab_unused __ksymtab_strings __param
> >   01     .data .data.cacheline_aligned .data.read_mostly
> > .data.init_task .data.page_aligned .init.text .init.data .init.setup
> > .initcall.init .con_initcall.init .altinstructions
> > .altinstr_replacement .exit.text .init.ramfs .bss
> >   02     .vsyscall_0 .xtime_lock .vxtime .vgetcpu_mode .sys_tz
> > .sysctl_vsyscall .xtime .jiffies .vsyscall_1 .vsyscall_2 .vsyscall_3
> >   03
> >
> 
> Hi Magnus,
> 
> I think this got introduced because of Ian Cambell's patch for creating
> PT_NOTE headers. Can you please try attached patch. I think it should
> fix the issue.

You are right, the patch solves the problem. It is now possible to use
kexec on x86_64 to reboot into a vmlinux built from 2.6.19-rc1 + your
patch.

Nice work, thanks!

/ magnus

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