/srv/irclogs.ubuntu.com/2012/06/25/#ubuntu-kernel.txt

=== rsalveti` is now known as rsalveti
mendalonanybody know if the new (2.6.35+) rc-core-based kernel modules can by used to do ir blaster stuff? i want to transmit ir codes through a homebrew serial ir blaster without using lircd.05:03
ppisatimoin07:37
smbppisati, morning07:37
ckingppisati, good morning!07:37
_jmp_morning ppisati smb cking 07:38
apwmoin08:24
ckingmore coffee...08:30
mendalonanybody know if the new (2.6.35+) rc-core-based kernel modules can by used to do ir blaster stuff? i want to transmit ir codes through a homebrew serial ir blaster without using lircd.09:08
* ppisati is melting...09:55
* abogani is wondering about where exactly ppisati is melting ..09:58
* ppisati -> lunch12:20
=== yofel_ is now known as yofel
argesherton, hello14:18
hertonarges, hi14:18
argesherton, about the systemtap bug. you mentioned using --only-keep-debug, would this be for reducing the size of the ddebs or for another purpose?14:19
hertonarges, just for reducing the size. I think we don't strip the debug .ko's at the moment, I did a quick look and didn't found anything14:19
argesherton, ok maybe that's something to do for future work. i think its a good idea since the ddebs are very large.14:21
hertonarges, yes, I agree, just noticed we could be stripping and keeping only the debug symbols while looking at that change14:22
argesok14:23
* ogasawara back in 2014:40
smoserok everyone, its that time of the day again, where smoser exposes his grave ignorance!14:41
smoseri'm thinking about bug 101669514:42
ubot2Launchpad bug 1016695 in cloud-init "add console=tty0 to cloud-image kernel boot parameters" [Wishlist,New] https://launchpad.net/bugs/101669514:42
smosersummary is that upstart messages (and stdout of 'console output' jobs it starts) go to the /dev/console device.14:43
smoserand getting that console device set to the right place is kind of difficult if you're targetting a one-size-fits-all image (like the cloud-images).14:43
smoseri can think of 2 possible ways of making this nicer.14:44
smosera.) some kernel "tee device" that would take writes to /dev/console and just write to multiple devices (ie, what 'tee file1 file2 file3' would do)14:45
smoserb.) some way to more intelligently set where writes to /dev/console end up.14:45
smosersmb, any thoughts?14:46
smbsmoser, Yes, I think that I need to think about it but feel like saying no-way to a) 14:47
smoseryeah, kernel tee device probably isn't the right place, as we could probably get the same with a user-land fifo. it just takes another process.14:48
smbsmoser, The early boot messages probably not (until any user-space is up). But from looking last and some experiments, through you can have console= multiple times, the kernel has some "preferred" console concept and that likely is there for a reason.14:52
smosersmb, right. multiple console= is acceptable and nice.14:53
smoserand it generlly selects the last entry in the parameters to tie to /dev/console14:53
smoseri'm not sure what happens if hte last entry is non-existant (ie, 'console=ttyS0' when there is no ttyS0. i think it probably does at least somethign sane).14:53
smoserso basically... the kernel does a pretty good job, but after init is started its more complex.14:54
smoser(this is where you probably say to me "not my problem"  :) )14:54
smbHeh, probably. Well, I wonder what could be done in syslog config... I believe there is now a single line for it, but maybe that could also become multiple... Though I would want to play around before I boldly state such a thing14:57
smbsmoser, Hm, ok, so reading this through more carefully it sounds more like something that whatever carries on with console output from init/upstart would need the concept of multiple consoles. syslogd is no good there and the kernel handles it that way (just /dev/console is always just one console)15:06
smosersmb, right. bsaically, init (upstart) would have to hook the processes' stdout, stderr to something that it  (or some other "tee like thing") then wrote to multiple places.15:09
smbsmoser, Otherwise the only other option would be to make cloud-init test various options and then modify the command line for the next boot. If having the first boot not show then is acceptable15:13
smosernext boot is useless.15:13
smoserbut yeah, that is easy[er]15:13
ckinghrm, libreoffice spreadsheet kinda chokes on > 90K samples in a graph, need more memory :-)15:15
rtgcking, you should use something more powerful then an Atom.15:15
smbNot sure whether that part of upstart could be more knowledgable than to just go for console. But then there will always be cases (ok maybe not with images on the cloud) where ttyS0 is present but unused...15:15
ckingrtg, I'm using an i5 @ 2.6GHz with 6 GB15:16
smosersmb, well, present but unused is fine.15:16
rtgcking, that seems like it ought to be enough15:16
ckingnot for the graphs I'm crunching15:16
smoserie, i dont really care about writing to additional places. just, ideally, want to make sure that if someone goes looking for messages, they see them.15:16
smbsmoser, I guess not when you have a Xen guest with a serial defined... You still would want to use hvc015:17
smoseryeah, its difficult.15:17
smoser:)15:17
smoseri think that the best thing to do would be to write a bunch of places, basically anything likely to be watched that is available.15:18
smoserand to have init mimic that basic behavior15:18
smbsmoser, Yes, true. Which at the current state of things really would make me say not so much my problem because the kernel messages do go multiple ways. I know that is evasive... ;)15:19
smosersmb, well, the only issue ihave with the kernel behavior is that i have to load up the command line manually with a bunch of "likely" places.15:20
* cking spots a trend which means he has to re-do a bunch of tests, *sigh*15:20
smoserand i'm not aware of the behavior if the last one in the list happens to be non-existant.15:20
smoserie: 'console=tty0 console=ttyS0 console=hvc0' without a hvc015:21
smbsmoser, probably does the right thing (though it should be tested). One drawback is that the more you have there more load/delay there may be. But then you cannot make this work for everyone in all cases. 15:25
smbsmoser, Even assuming this can be changed at some point from user-space, it is probably only the guest configuration on the host that would be able to say what the console is and I am not sure all possible virtualisation types would provide some way to find out...15:27
smosersmb, yeha. i didn't htink there was any clear simple way to get this right.15:33
smoserbut, thanks for your input.15:33
apwrtg, any idea how to list subsribed multicast groups ?15:52
rtgapw, not from memory15:52
rtgapw, would there be anything in dmesg ?15:52
* apw finds it by luck15:53
apwrtg, ip maddr does it15:53
rtgapw, makes sense15:53
evapw: hi. Did you happen to see my email about kernel oopses a little while back?15:58
apwev, do we normally get cores from crashes, that'd not be a common config16:05
apwand something we'd not want to be sending anywhere somewhere i suspect16:06
evah, interesting. What are you looking for, and what would be a reasonable algorithm for the signature of it?16:06
apwthere is a common oops format in dmesg/messages 16:07
apwwe are sending those in already though right, in the apport enabled world16:07
evoh I'm misreading my own email16:07
evright16:07
evindeed, we are sending oopses through16:07
evbut we don't have a signature for them16:08
apwi'd assume signatures could be done the way you do them for any other C style applkication16:08
apwthe only special is there are ? entries which generally can be ignored16:08
evthus my proposal of ext4_get_acl+0x80/0x210:d_splice_alias+0x40/0x50:ext4_check_acl+0x4a/0x90:acl_permission_check+0x97/0xa0:generic_permission+0x25/0xc0:inode_permission+0x99/0xd0 for https://launchpadlibrarian.net/79771442/OopsText.txt16:08
evright16:08
apwyou might also want to include the type of the blammo16:10
apwso thats a 'kernel paging request'16:11
evapw: okay, will do. And you're happy with the rest of that as a signature?16:11
evwith the type included, that is16:11
apwev, yeah i think until we try it we're not going to see what triggers overly commonisation or over differntiation16:13
evfair point16:13
apwev, when you do other C things do you include the +xx parts ?16:13
evapw: until we have a fully retraced stacktrace, yes: http://people.canonical.com/~ubuntu-archive/apport-duplicates/address/_usr_bin_Thunar_616:14
* ppisati -> gym16:21
evapw: out of curiosity, why don't we want to capture VmCore files?16:22
apwits not a simple thing to do, and not enabled by default16:22
apwas your machine has to crash and reboot to do it, we normally try and hang one and keep going, for least supprise16:23
evah, understood16:23
apwand the chances of the vmcore not having something sensitive in it is very small16:24
evapw: thanks for all the advice16:28
apwev thanks for looking at it16:28
=== rtg is now known as rtg-lunch
ckingapw, I've now collected and graphed way too much data for the low-latency kernel and I'll try and get it written up tomorrow. I find the data still rather perplexing18:36
apwcking, that sounds 'bad'18:38
ckingthe results kind of match what we expect in some cases, but not in others, which I find perplexing18:39
=== rtg-lunch is now known as rtg
* ppisati -> out for dinner18:52
laserbledHi, how do i disable a option in config file for compiling...is it a 'n' or a '0" or a m ?, also can someone help me with fixing up a config file for minimum size vanilla version18:56
apwlaserbled, its # CONFIG_FOO is not set19:17
laserbledapw, great, do I have to comment it out using # too ?19:18
laserbledok, I am assuming that doesn't resolve as a comment then19:20
apw# CONFIG_FOO is not set 19:21
apwis a specific syntax meaning =n19:21
laserbledapw,  yes, got it. can you tell me what does a m stand for ? 19:23
apwmodular19:23
laserbledapw, great. thanks a lot for the info.19:26
apwnp19:28
* rtg -> EOD20:58
skaetogasawara, do you have the bug number for the arm fix we may try to include?21:57
ppisatiskaet: didn't fill them yet21:57
ppisatiskaet: i'll do it now21:57
skaetthanks ppisati :)21:57
ppisatiskaet: bug 101771722:16
ubot2Launchpad bug 1017717 in linux "Severe filesystem corruption on beagle board" [Undecided,New] https://launchpad.net/bugs/101771722:16
ppisatiskaet: bug 101771822:16
ubot2Launchpad bug 1017718 in linux "Usb hub not working on beagle board" [Undecided,New] https://launchpad.net/bugs/101771822:16
ppisatiogasawara: ^^22:16
skaetthanks ppisati.   What should the priorities be for these?22:17
ppisatifirst one is already fixed (i've the patch here) for the second one i'm still investigating one thing (and i hope to clear it ASAP...)22:18
* skaet noticing Undecided, New and figures they're probably In Progress , High22:18
ppisatiah right, forgot the status22:18
ppisatiright22:18
ppisatiin progress, high is good22:18
skaetppisati, have noted it on the bugs.22:22

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