Hi,
Since the old "in-order-execution" Intel CPUs like the Intel Atom N270
(known for being installed in many Netbooks and Nettops) are not
sensitive for "Meltdown" & "Spectre" , wouldn't it be a good idea to
exclude these anyway "weak" CPUs from the costly patches by default?
Browsing the web, I can "feel the difference" if the matching kernel
options are applied on such a device.
BR
C.Krüger
On Sat 2018-05-19 21:53:02, Christian Kr?ger wrote:
> Hi,
>
> Since the old "in-order-execution" Intel CPUs like the Intel Atom N270
> (known for being installed in many Netbooks and Nettops) are not sensitive
> for "Meltdown" & "Spectre" , wouldn't it be a good idea to exclude these
> anyway "weak" CPUs from the costly patches by default?
>
> Browsing the web, I can "feel the difference" if the matching kernel options
> are applied on such a device.
Can you also measure the difference? Placebo effect is hard to avoid.
But yes, we do not need to do workarounds on non-buggy machines...
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
On 2018 Mai 23, Pavel Machek wrote:
> On Sat 2018-05-19 21:53:02, Christian Krüger wrote:
> > Hi,
> >
> > Since the old "in-order-execution" Intel CPUs like the Intel Atom N270
> > (known for being installed in many Netbooks and Nettops) are not sensitive
> > for "Meltdown" & "Spectre" , wouldn't it be a good idea to exclude these
> > anyway "weak" CPUs from the costly patches by default?
> >
> > Browsing the web, I can "feel the difference" if the matching kernel options
> > are applied on such a device.
>
> Can you also measure the difference? Placebo effect is hard to avoid.
>
> But yes, we do not need to do workarounds on non-buggy machines...
>
> Pavel
On my Atom N270 there doesn't seem to be any workaround active with
kernel 4.14.42:
localhost ~ # cat /sys/devices/system/cpu/vulnerabilities/*
Not affected
Not affected
Not affected
Christian, did you verified the mitigations are active on your system?
What kernels are affected?
--
Regards,
Johannes
Am 23.05.2018 um 19:07 schrieb Johannes Hirte:
> On 2018 Mai 23, Pavel Machek wrote:
>> On Sat 2018-05-19 21:53:02, Christian Krüger wrote:
>>> Hi,
>>>
>>> Since the old "in-order-execution" Intel CPUs like the Intel Atom N270
>>> (known for being installed in many Netbooks and Nettops) are not sensitive
>>> for "Meltdown" & "Spectre" , wouldn't it be a good idea to exclude these
>>> anyway "weak" CPUs from the costly patches by default?
>>>
>>> Browsing the web, I can "feel the difference" if the matching kernel options
>>> are applied on such a device.
>>
>> Can you also measure the difference? Placebo effect is hard to avoid.
>>
>> But yes, we do not need to do workarounds on non-buggy machines...
>>
>> Pavel
>
> On my Atom N270 there doesn't seem to be any workaround active with
> kernel 4.14.42:
>
> localhost ~ # cat /sys/devices/system/cpu/vulnerabilities/*
> Not affected
> Not affected
> Not affected
>
> Christian, did you verified the mitigations are active on your system?
> What kernels are affected?
>
$ uname -a
Linux user-device 3.13.0-143-generic #192-Ubuntu SMP Tue Feb 27 10:46:44
UTC 2018 i686 i686 i686 GNU/Linux
$ cat /sys/devices/system/cpu/vulnerabilities/*
Vulnerable
Mittigation: OSB (observable speculation barrier, Intel v6)
Mittigation: Full generic repoline
OK, so I've updated the OS on my (usually off-line) Netbook:
$ uname -a
Linux user-device 3.13.0-149-generic #199-Ubuntu SMP Thu May 17 10:12:57
UTC 2018 i686 i686 i686 GNU/Linux
$ cat /sys/devices/system/cpu/vulnerabilities/*
Not affected
Not affected
Not affected
Not affected
Conclusion:
Don't bother others before not checking the latest version. (Actually
this is the first time it made a difference... ).
Sorry for the noise and thanks for listening and all the great work!
Christian