Re: vmcore file 0 size in x86_64

[Chandan12 K <chandan12.k@xxxxxxx>]

Hi,

I checked.. through and fond out that
one of the following check condition is failing

 516        
if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
    517      
          (ehdr.e_type != ET_CORE) ||
    518      
          !vmcore_elf_check_arch(&ehdr) ||
    519      
          ehdr.e_ident[EI_CLASS] != ELFCLASS64
||
    520      
          ehdr.e_ident[EI_VERSION] != EV_CURRENT
||
    521      
          ehdr.e_version != EV_CURRENT ||
    522      
          ehdr.e_ehsize != sizeof(Elf64_Ehdr)
||
    523      
          ehdr.e_phentsize != sizeof(Elf64_Phdr)
||
    524      
          ehdr.e_phnum == 0) {
    525      
          printk(KERN_WARNING "Warning: Core
image elf header is not"
    526      
                     
            "sane:%ld\n",elfcorehdr_addr);
    527      
        return -EINVAL
    528      
  }

If I comment this return at line 527,
then the code flows through and the vmcore is getting generated. 

However, I am facing a new issue, my
user space is 32 bit and the kernel is 64 bit. And I want to access the
high memory (high_memory - BACK_UP_SIZE) area of the previous/primary kernel.
Where some log data I had saved. The toral RAM is 8GB.

As the 32 bit pointers could not reach
there... means simple file operations lseek() , read etc are not working..
to access some region around 8GB.

Can you please suggest me some way to
reach that memory and read my raw data from the user space. 

I am able to read the data from kernel
space( a simple kernel module via /proc interface to transfer the data
from kernel to user space using physical address of the primary kernel).



Chandan Kumar
TCS Mumbai

Chandan12 K <chandan12.k@xxxxxxx>
Sent by: kexec-bounces@xxxxxxxxxxxxxxxxxxx

08/13/2009 03:40 PM

To	kexec@xxxxxxxxxxxxxxxxxxx
cc
Subject	vmcore file 0 size in x86_64

Hi, 

Adding boot logs 

NET: Registered protocol family 1 
audit: initializing netlink socket (disabled) 
type=2000 audit(1250069944.104:1): initialized 
VFS: Disk quotas dquot_6.5.1 
Dquot-cache hash table entries: 512 (order 0, 4096 bytes)
Warning: Core image elf header is notsane 
Kdump: vmcore not initialized 
Registering unionfs 2.2-mm 
msgmni has been set to 90 
io scheduler noop registered 
io scheduler anticipatory registered


however, similar case has already been discussed in other mailing lists
with vivek. The only difference is that, I am not using redhat system and
dont have any user level kexel tools.   

https://lists.linux-foundation.org/pipermail/fastboot/2007-January/012572.html

The kernel command line of capture kernel (kexe'ed kernel) : Kernel command
line: root=/dev/nfs rw console=ttyS0,115200 ip=::::::dhcp selinux=0 noacpi
maxcpus=1 memmap=exactmap memmap=640K@0K memmap=64876K@16384K elfcorehdr=81260K


Command line for the Primary kernel : root=/dev/nfs rw console=ttyS0,115200
ip=::::::dhcp crashkernel=64M@16M 

kexec command used : kexec -p bzImage --append="root=/dev/nfs rw console=ttyS0,115200
ip=::::::dhcp selinux=0 noacpi maxcpus=1" 

Kconfig options : 

CONFIG_CRASH_DUMP=y 
CONFIG_PHYSICAL_START=0x200000 
CONFIG_RELOCATABLE=y 
CONFIG_PHYSICAL_ALIGN=0x200000

Please suggest. 


Chandan

Dave Anderson <anderson@xxxxxxxxxx>
Sent by: crash-utility-bounces@xxxxxxxxxx

08/12/2009 07:39 PM

Please respond to
"Discussion list for crash utility usage,        maintenance and development" <crash-utility@xxxxxxxxxx>

To	"Discussion list for crash utility usage,        maintenance and development" <crash-utility@xxxxxxxxxx>
cc
Subject	Re: [Crash-utility] vmcore file size 0 on x86_64

Forwarded to kexec list:

http://lists.infradead.org/pipermail/kexec/2009-August/003474.html

----- "Chandan12 K" <chandan12.k@xxxxxxx> wrote:

> Hi,
> 
> I am little new in this mailing list. I just wondered if anybody could
> help me regarding the vmcore file generation. I ran kexec on my x86_64
> machine, and the /proc/vmcore file is created with zero size.
> 
> However, even if I read the /dev/oldmem file, I am only able to read
> till 16M. I guess I am only able to read till the 'X', where X is
> crashkernel=Y@X.
> 
> Moreover, My machine seems to have 32 bit user space and ofcourse,
64
> bit kernel space.
> 
> Appreciate any response.
> 
> Chandan Kumar
> ____________________________________________ =====-----=====-----=====
> Notice: The information contained in this e-mail
> message and/or attachments to it may contain
> confidential or privileged information. If you are
> not the intended recipient, any dissemination, use,
> review, distribution, printing or copying of the
> information contained in this e-mail message
> and/or attachments to it are strictly prohibited. If
> you have received this communication in error,
> please notify us by reply e-mail or telephone and
> immediately and permanently delete the message
> and any attachments. Thank you 
> --
> Crash-utility mailing list
> Crash-utility@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/crash-utility

--
Crash-utility mailing list
Crash-utility@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/crash-utility

ForwardSourceID:NT0000987A     
=====-----=====-----=====
Notice: The information contained in this e-mail
message and/or attachments to it may contain 
confidential or privileged information. If you are 
not the intended recipient, any dissemination, use, 
review, distribution, printing or copying of the 
information contained in this e-mail message 
and/or attachments to it are strictly prohibited. If 
you have received this communication in error, 
please notify us by reply e-mail or telephone and 
immediately and permanently delete the message 
and any attachments. Thank you


_______________________________________________
kexec mailing list
kexec@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/kexec

ForwardSourceID:NT000098BE     

Chandan Kumar
TCS Mumbai
=====-----=====-----=====
Notice: The information contained in this e-mail
message and/or attachments to it may contain 
confidential or privileged information. If you are 
not the intended recipient, any dissemination, use, 
review, distribution, printing or copying of the 
information contained in this e-mail message 
and/or attachments to it are strictly prohibited. If 
you have received this communication in error, 
please notify us by reply e-mail or telephone and 
immediately and permanently delete the message 
and any attachments. Thank you


_______________________________________________
kexec mailing list
kexec@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/kexec

ForwardSourceID:NT0000994A
   
=====-----=====-----=====
Notice: The information contained in this e-mail
message and/or attachments to it may contain 
confidential or privileged information. If you are 
not the intended recipient, any dissemination, use, 
review, distribution, printing or copying of the 
information contained in this e-mail message 
and/or attachments to it are strictly prohibited. If 
you have received this communication in error, 
please notify us by reply e-mail or telephone and 
immediately and permanently delete the message 
and any attachments. Thank you


_______________________________________________
fastboot mailing list
fastboot@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/fastboot