[Xenomai-core] PRNG not seeded on AMD K7

[Xenomai-core] PRNG not seeded on AMD K7

[Jeroen Van den Keybus]

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When I try to open an ssh connection to or from a PC running Xenomai, I get
a 'PRNG not seeded' error. However, it only occurs when an RT application is
running (such as 'latency'). The computer on which this occurs is an AMD
K7-650. I've tested on a Pentium III 500 as well (nearly same .config) and
this error doesn't show up then.

Any idea of where I should start debugging ? I assume that PRNG stands
for 'Programmable Random Number Generator' or something like that.

Jeroen.

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Re: [Xenomai-core] PRNG not seeded on AMD K7

[Gilles Chanteperdrix]

Jeroen Van den Keybus wrote:
 > When I try to open an ssh connection to or from a PC running Xenomai, I get
 > a 'PRNG not seeded' error. However, it only occurs when an RT application is
 > running (such as 'latency'). The computer on which this occurs is an AMD
 > K7-650. I've tested on a Pentium III 500 as well (nearly same .config) and
 > this error doesn't show up then.
 > 
 > Any idea of where I should start debugging ? I assume that PRNG stands
 > for 'Programmable Random Number Generator' or something like that.

See in kernel configuration if you have the CONFIG_HW_RANDOM option
enabled, if the module is loaded when the error occurs, and if
/dev/urandom exists.

-- 


					    Gilles Chanteperdrix.

Re: [Xenomai-core] PRNG not seeded on AMD K7

[Gilles Chanteperdrix]

Gilles Chanteperdrix wrote:
 > Jeroen Van den Keybus wrote:
 >  > When I try to open an ssh connection to or from a PC running Xenomai, I get
 >  > a 'PRNG not seeded' error. However, it only occurs when an RT application is
 >  > running (such as 'latency'). The computer on which this occurs is an AMD
 >  > K7-650. I've tested on a Pentium III 500 as well (nearly same .config) and
 >  > this error doesn't show up then.
 >  > 
 >  > Any idea of where I should start debugging ? I assume that PRNG stands
 >  > for 'Programmable Random Number Generator' or something like that.
 > 
 > See in kernel configuration if you have the CONFIG_HW_RANDOM option
 > enabled, if the module is loaded when the error occurs, and if
 > /dev/urandom exists.

CONFIG_HW_RANDOM is for the /dev/hwrandom device, and libssl uses
/dev/random or /dev/urandom. /dev/urandom is seeded at boot-time
by a script (/etc/init.d/urandom on Debian).

So FPU hardware, as mentioned by Philippe, is a better candidate.

-- 


					    Gilles Chanteperdrix.

Re: [Xenomai-core] PRNG not seeded on AMD K7

[Philippe Gerum]

Jeroen Van den Keybus wrote:
> When I try to open an ssh connection to or from a PC running Xenomai, I 
> get a 'PRNG not seeded' error. However, it only occurs when an RT 
> application is running (such as 'latency'). The computer on which this 
> occurs is an AMD K7-650. I've tested on a Pentium III 500 as well 
> (nearly same .config) and this error doesn't show up then.
>  
> Any idea of where I should start debugging ? I assume that PRNG stands 
> for 'Programmable Random Number Generator' or something like that.

First guess: something might be perturbated by Xeno's FPU management on AMD; the 
fact that /dev/random might be involved in the issue would tend to confirm this.
Does disabling CONFIG_XENO_HW_FPU on the AMD box change anything?

>  
> Jeroen.
>  
> 
> 
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> 
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-- 

Philippe.