Spontaneous reboots with splash
Mehmet Erol Sanliturk
m.e.sanliturk at gmail.com
Thu Oct 22 16:18:55 UTC 2015
On Thu, Oct 22, 2015 at 8:14 AM, Andrea Venturoli <ml at netfence.it> wrote:
> On 10/22/15 14:18, Mehmet Erol Sanliturk wrote:
>
> If you have two identical computers with the same programs running :
>> One is working correctly , but other one is booting arbitrarily :
>>
>
> I've got another identical box; I'll restore a dump on this and see if the
> behaviour is the same.
>
>
>
>
> Therefore , there is a necessity to check that
>>
>> - processor is working correctly
>>
>
> CPU Burn-in says yes.
>
>
>
> - memories are working correctly
>>
>
> Memtest 86+ says so.
>
>
>
> - memory management chips are working correctly .
>>
>
> I have no idea how to check. How do I do this?
>
>
>
If memory tests are showing memories are working correctly , it is possible
to say that memory management chips are also working correctly . Otherwise
, it is not possible to write into and read from chips correctly .
If memory chips fail , by testing with correctly working chips known , the
problem may be attributed to memory management chips .
Another possibility is the Watt level of Power Supply : If the required
watts is exceeding the existent power supply watts level , it may cause
reboots when power use increases beyond its capacity .
Another possibility is power supply is cutting power spontaneously or
causing fluctuations .
>
> Another problem may be a program which is causing generation of an
>> invalid address showing boot start code and jumping into it . This is
>> very easy for a i386 real mode program .
>>
>
> In that case this program would be FreeBSD! That's why I'm asking here.
>
>
>
>
If you can isolate the program causing boots , it will be possible to check
its sources and binary file .
>
> Another possibility is that a program is broken ( contains an invalid
>> address )
>>
> > in HDD . When it starts to working , it jumps to that broken address
> and this
> > may start the boot .
>
> Would a userland program be allowed to do this???
>
>
>
Let's assume that CPU is not over-heated and is not rebooting the computer
like motherboard is powered .
Let's assume that there is no any malicious program part to cause rebooting
.
A broken network card may corrupt data and may cause serious problems .
The remaining possibility is that instruction counter value is destroyed in
a program and showing the BIOS boot code area . To reboot the computer ,
it is necessary to start BIOS boot code
This may occur also during BIOS related calls . Instead of a proper
interrupt code , boot part is invoked .
Otherwise we will say that within FreeBSD OS parts , there is a point that
, instead of a proper shut down , it is directly rebooting the computer by
calling BIOS boot code . Checking panic points and searching OS sources for
such a reboot code ( without any error message and request approval from
the user ) existence may help .
Here the most important part is to find the program part which is causing
the reboots . Studying this program part will reveal the reason and ,
therefore the cure .
I can not say any correct sentence here about FreeBSD internals due to (
not sufficient knowledge ) .
Since that computer is not working properly , you can do the following :
Reinstall OS into a spare disk and check with it .
This will identify whether problem is caused by the presently installed OS
or not .
If it can execute 64-bits OS , testing with such an OS will identify effect
of OS or hardware .
>
> bye & Thanks
> av.
>
Mehmet Erol Sanliturk
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