Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Eric W. Biederman]

"Prabhakar K." <krishkar99@yahoo.com> writes:

> Hi - After my previous posting I was able to make some progress.
>
> When I do
>
> kexec -l vmlinux --append="init 1 root=/dev/hda2" --console-serial
>
> and 
> kexec -e,
>
> I get message:
>
> Starting new kernel
> I'm in purgatory
>
> And after that it still boots from BIOS (to the same first kernel).
>
> Whats the problem here?

I would recommend instrumenting up purgatory and then your target kernel.

It is quite possible the problem is in your backport.

> Also do I need kdump again in addition to the latest kexec tools?
> When I do:
> #chkconfig kdump on
> error reading information on service kdump
> #service kdump start
> Bad core dump start addres: start

The user space kdump stuff is just a user space wrapper, that creates
a useful initrd etc.


> What am I missing here?

The appropriate list.  Discussion of all things kexec has moved to the kexec
list at infradead which I have cc'd.

Eric

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Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Prabhakar K.]

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> Hi - After my previous posting I was able to make some progress.
>
> When I do
>
> kexec -l vmlinux --append="init 1 root=/dev/hda2" --console-serial
>
> and 
> kexec -e,
>
> I get message:
>
> Starting new kernel
> I'm in purgatory
>
> And after that it still boots from BIOS (to the same first kernel).
>
> Whats the problem here?

I would recommend instrumenting up purgatory and then your target kernel.

It is quite possible the problem is in your backport.
>>>> I have instrumented the purgatory code. when I run kexec -e, It hangs for a while at 
sha256_starts(&ctx); in the function verify_sha256_digest(), and then reboots to the first kernel (from BIOS). I have put debug prints in sha256_starts, but none of those are executed.
Interestingly, the same function sha256_starts is executed during kexec -l, which is called as part of update_purgatory( )( when my_load( ) is called from kexec.c).so its surprise why the same function is giving problems when kexec -e is run.

> What am I missing here?

The appropriate list.  Discussion of all things kexec has moved to the kexec
list at infradead which I have cc'd.

>>> Thanks Eric. For directing me to the right mailing list.

I am not subscribed to the list, so please CC me. Thanks !!
Regards,Prabhakar


      

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Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Eric W. Biederman]

"Prabhakar K." <krishkar99@yahoo.com> writes:

>> Hi - After my previous posting I was able to make some progress.
>>
>> When I do
>>
>> kexec -l vmlinux --append="init 1 root=/dev/hda2" --console-serial
>>
>> and 
>> kexec -e,
>>
>> I get message:
>>
>> Starting new kernel
>> I'm in purgatory
>>
>> And after that it still boots from BIOS (to the same first kernel).
>>
>> Whats the problem here?
>
> I would recommend instrumenting up purgatory and then your target kernel.
>
> It is quite possible the problem is in your backport.
>
>>>>>
>  I have instrumented the purgatory code. when I run kexec -e, It hangs for a
> while at 
> sha256_starts(&ctx); in the function verify_sha256_digest(), and then reboots
> to the first kernel (from BIOS). I have put debug prints in sha256_starts, but
> none of those are executed.
>
> Interestingly, the same function sha256_starts is executed during kexec -l,
> which is called as part of update_purgatory( )( when my_load( ) is called from
> kexec.c).
> so its surprise why the same function is giving problems when kexec -e is run.

Do you by any chance have a watchdog you are not petting?

Eric


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Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Prabhakar K.]

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From: Eric W. Biederman <ebiederm@xmission.com>
Subject: Re: [Fastboot] kexec - 2.6.14 - loads BIOS again
To: "Prabhakar K." <krishkar99@yahoo.com>
Cc: "Kexec Mailing List" <kexec@lists.infradead.org>, fastboot@lists.linux-foundation.org
Date: Tuesday, September 29, 2009, 6:11 AM

"Prabhakar K." <krishkar99@yahoo.com> writes:

>> Hi - After my previous posting I was able to make some progress.
>>
>> When I do
>>
>> kexec -l vmlinux --append="init 1 root=/dev/hda2" --console-serial
>>
>> and 
>> kexec -e,
>>
>> I get message:
>>
>> Starting new kernel
>> I'm in purgatory
>>
>> And after that it still boots from BIOS (to the same first kernel).
>>
>> Whats the problem here?
>
> I would recommend instrumenting up purgatory and then your target kernel.
>
> It is quite possible the problem is in your backport.
>
>>>>>
>  I have instrumented the purgatory code. when I run kexec -e, It hangs for a
> while at 
> sha256_starts(&ctx); in the function verify_sha256_digest(), and then reboots
> to the first kernel (from BIOS). I have put debug prints in sha256_starts, but
> none of those are executed.
>
> Interestingly, the same function sha256_starts is executed during kexec -l,
> which is called as part of update_purgatory( )( when my_load( ) is called from
> kexec.c).
> so its surprise why the same function is giving problems when kexec -e is run.

Do you by any chance have a watchdog you are not petting?
>> Yes, we do have software watchdog and hardware watchdog. I disabled software watchdog and I think the reason for resetting to the first kernel can be explained due to hardware watchdog kicking in.
To try out a different version of the kexec, I took kexec version 20080227 from http://www.kernel.org/pub/linux/kernel/people/horms/kexec-tools/and instrumented that code as well. With this, I was able to see the sha 256 verification done during kexec -e and also the post verification of purgatory code. And it hangs there (does not reboot to the first kernel).
So, any conclusions based on these ? Please CC me in reply. Thanks !!

Eric


      

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Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Prabhakar K.]

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I have back ported to multiple versions of different kexec-tools. Also I disabled watchdogs so that the first kernel reboot is not kicked in.Now, with all those kexec-tools I see that it hangs after post_verification_setup_arch( ).And I had to hard reboot the router box.
Is there a specific kexec tools that is known to work with 2.6.14 ? Or any additional changes needed ?
Any inputs welcome , thanks in advance !!
Please CC me in reply.
Regards,Prabhakar

--- On Tue, 9/29/09, Eric W. Biederman <ebiederm@xmission.com> wrote:

From: Eric W. Biederman <ebiederm@xmission.com>
Subject: Re: [Fastboot] kexec - 2.6.14 - loads BIOS again
To: "Prabhakar K." <krishkar99@yahoo.com>
Cc: "Kexec Mailing List" <kexec@lists.infradead.org>, fastboot@lists.linux-foundation.org
Date: Tuesday, September 29, 2009, 6:11 AM

"Prabhakar K." <krishkar99@yahoo.com> writes:

>> Hi - After my previous posting I was able to make some progress.
>>
>> When I do
>>
>> kexec -l vmlinux --append="init 1 root=/dev/hda2" --console-serial
>>
>> and 
>> kexec -e,
>>
>> I get message:
>>
>> Starting new kernel
>> I'm in purgatory
>>
>> And after that it still boots from BIOS (to the same first kernel).
>>
>> Whats the problem here?
>
> I would recommend instrumenting up purgatory and then your target kernel.
>
> It is quite possible the problem is in your backport.
>
>>>>>
>  I have instrumented the purgatory code. when I run kexec -e, It hangs for a
> while at 
> sha256_starts(&ctx); in the function verify_sha256_digest(), and then reboots
> to the first kernel (from BIOS). I have put debug prints in sha256_starts, but
> none of those are executed.
>
> Interestingly, the same function sha256_starts is executed during kexec -l,
> which is called as part of update_purgatory( )( when my_load( ) is called from
> kexec.c).
> so its surprise why the same function is giving problems when kexec -e is run.

Do you by any chance have a watchdog you are not petting?

Eric




      

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Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Prabhakar K.]

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Sending again as it is not posted yet !!
I have back ported to multiple versions of different kexec-tools. Also I disabled watchdogs so that the first kernel reboot is not kicked in.Now, with all those kexec-tools I see that it hangs after post_verification_setup_arch( ).And I had to hard reboot the router box.
Is there a specific kexec tools that is known to work with 2.6.14 ? Or any additional changes needed ?
Any inputs welcome , thanks in advance !!
Please CC me in reply.
Regards,Prabhakar
--- On Tue, 9/29/09, Eric W. Biederman <ebiederm@xmission.com> wrote:

From: Eric W. Biederman <ebiederm@xmission.com>
Subject: Re: [Fastboot] kexec - 2.6.14 - loads BIOS again
To: "Prabhakar K." <krishkar99@yahoo.com>
Cc: "Kexec Mailing List" <kexec@lists.infradead.org>, fastboot@lists.linux-foundation.org
Date: Tuesday, September 29, 2009, 6:11 AM

"Prabhakar K." <krishkar99@yahoo.com> writes:

>> Hi - After my previous posting I was able to make some progress.
>>
>> When I do
>>
>> kexec -l vmlinux --append="init 1 root=/dev/hda2" --console-serial
>>
>> and 
>> kexec -e,
>>
>> I get message:
>>
>> Starting new kernel
>> I'm in purgatory
>>
>> And after that it still boots from BIOS (to the same first kernel).
>>
>> Whats the problem here?
>
> I would recommend instrumenting up purgatory and then your target kernel.
>
> It is quite possible the problem is in your backport.
>
>>>>>
>  I have instrumented the purgatory code. when I run kexec -e, It hangs for a
> while at 
> sha256_starts(&ctx); in the function verify_sha256_digest(), and then reboots
> to the first kernel (from BIOS). I have put debug prints in sha256_starts, but
> none of those are executed.
>
> Interestingly, the same function sha256_starts is executed during kexec -l,
> which is called as part of update_purgatory( )( when my_load( ) is called from
> kexec.c).
> so its surprise why the same function is giving problems when kexec -e is run.

Do you by any chance have a watchdog you are not petting?

Eric



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Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Eric W. Biederman]

"Prabhakar K." <krishkar99@yahoo.com> writes:

> Sending again as it is not posted yet !!
>
> I have back ported to multiple versions of different kexec-tools. Also I
> disabled watchdogs so that the first kernel reboot is not kicked in.
> Now, with all those kexec-tools I see that it hangs
> after post_verification_setup_arch( ).
> And I had to hard reboot the router box.
>
> Is there a specific kexec tools that is known to work with 2.6.14 ? Or any
> additional changes needed ?

Almost certainly if you are getting as far as kexec-tools you are dying
someplace early in your target kernel.


> Any inputs welcome , thanks in advance !!
>
> Please CC me in reply.

Eric

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

Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Prabhakar K.]

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From: Eric W. Biederman <ebiederm@xmission.com>
Subject: Re: [Fastboot] kexec - 2.6.14 - loads BIOS again
To: "Prabhakar K." <krishkar99@yahoo.com>
Cc: "Kexec Mailing List" <kexec@lists.infradead.org>, fastboot@lists.linux-foundation.org
Date: Thursday, October 1, 2009, 6:29 AM

"Prabhakar K." <krishkar99@yahoo.com> writes:

> Sending again as it is not posted yet !!
>
> I have back ported to multiple versions of different kexec-tools. Also I
> disabled watchdogs so that the first kernel reboot is not kicked in.
> Now, with all those kexec-tools I see that it hangs
> after post_verification_setup_arch( ).
> And I had to hard reboot the router box.
>
> Is there a specific kexec tools that is known to work with 2.6.14 ? Or any
> additional changes needed ?

Almost certainly if you are getting as far as kexec-tools you are dying
someplace early in your target kernel.

>>> OK. What piece of code can cause in the target kernel to die ?Can I take any working bzImage or vmlinux of a linux kernel(for that matter any linux kernel) and load that as my target kernel ? or does this has any restriction ?thanks for your input !!

> Any inputs welcome , thanks in advance !!
>

Please CC me in reply.

Eric
--- On Thu, 10/1/09, Eric W. Biederman <ebiederm@xmission.com> wrote:

From: Eric W. Biederman <ebiederm@xmission.com>
Subject: Re: [Fastboot] kexec - 2.6.14 - loads BIOS again
To: "Prabhakar K." <krishkar99@yahoo.com>
Cc: "Kexec Mailing List" <kexec@lists.infradead.org>, fastboot@lists.linux-foundation.org
Date: Thursday, October 1, 2009, 6:29 AM

"Prabhakar K." <krishkar99@yahoo.com> writes:

> Sending again as it is not posted yet !!
>
> I have back ported to multiple versions of different kexec-tools. Also I
> disabled watchdogs so that the first kernel reboot is not kicked in.
> Now, with all those kexec-tools I see that it hangs
> after post_verification_setup_arch( ).
> And I had to hard reboot the router box.
>
> Is there a specific kexec tools that is known to work with 2.6.14 ? Or any
> additional changes needed ?

Almost certainly if you are getting as far as kexec-tools you are dying
someplace early in your target kernel.


> Any inputs welcome , thanks in advance !!
>
> Please CC me in reply.

Eric



      

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Re: [Fastboot] kexec - 2.6.14 - loads BIOS again

[Eric W. Biederman]

"Prabhakar K." <krishkar99@yahoo.com> writes:

> From: Eric W. Biederman <ebiederm@xmission.com>
> Subject: Re: [Fastboot] kexec - 2.6.14 - loads BIOS again
> To: "Prabhakar K." <krishkar99@yahoo.com>
> Cc: "Kexec Mailing List" <kexec@lists.infradead.org>,
> fastboot@lists.linux-foundation.org
> Date: Thursday, October 1, 2009, 6:29 AM
>
> "Prabhakar K." <krishkar99@yahoo.com> writes:
>
>> Sending again as it is not posted yet !!
>>
>> I have back ported to multiple versions of different kexec-tools. Also I
>> disabled watchdogs so that the first kernel reboot is not kicked in.
>> Now, with all those kexec-tools I see that it hangs
>> after post_verification_setup_arch( ).
>> And I had to hard reboot the router box.
>>
>> Is there a specific kexec tools that is known to work with 2.6.14 ? Or any
>> additional changes needed ?
>
> Almost certainly if you are getting as far as kexec-tools you are dying
> someplace early in your target kernel.
>
>>>> OK. What piece of code can cause in the target kernel to die ?
> Can I take any working bzImage or vmlinux of a linux kernel(for that matter any
> linux kernel) and load that as my target kernel ? or does this has any
> restriction ?

Short of bugs in /sbin/kexec it is unrestricted.

Eric

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