vmcore file 0 size in x86_64

vmcore file 0 size in x86_64

[Chandan12 K]

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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@redhat.com> 
Sent by: crash-utility-bounces@redhat.com 
08/12/2009 07:39 PM 

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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@tcs.com> 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
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Chandan Kumar
TCS Mumbai
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Re: vmcore file 0 size in x86_64

[Chandan12 K]

[-- Attachment #1.1: Type: text/plain, Size: 7150 bytes --]

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@tcs.com> 
Sent by: kexec-bounces@lists.infradead.org
08/13/2009 03:40 PM

To
kexec@lists.infradead.org
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@redhat.com> 
Sent by: crash-utility-bounces@redhat.com 
08/12/2009 07:39 PM 

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



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"Discussion list for crash utility usage,        maintenance and 
development" <crash-utility@redhat.com> 
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@tcs.com> 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@redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility

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Chandan Kumar
TCS Mumbai
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Re: vmcore file 0 size in x86_64

[Eric W. Biederman]

Chandan12 K <chandan12.k@tcs.com> writes:

> 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).

Typically in user space that can be solved in a 32bit userspace
with FILE_OFFSET=64 or something like that.

There are 32bit syscalls that accept 64bit offsets to files.

Eric

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Re: vmcore file 0 size in x86_64

[Ken'ichi Ohmichi]

Hi,

Chandan12 K wrote:
> 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).

If compiling your user space program with tree options
(-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE),
it can access the high memory.


Thanks
Ken'ichi Ohmichi

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Re: vmcore file 0 size in x86_64

[Bernhard Walle]

Ken'ichi Ohmichi schrieb:
> 
> If compiling your user space program with tree options
> (-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE),
> it can access the high memory.

And it's important that you load the crashkernel with

 % kexec ... --elf64-core-headers

or at least *without* --elf32-core-headers since there is an
auto-detection in 'new' versions of kexec.


Regards,
Bernhard


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