gmane.linux.kernel.mentors

ISO 8601 Timestamp <-> UNIX Timestamp

Dan Luedtke — 2012-05-20T11:07:29

Hi everyone,

are there any functions to convert from and to ISO 8601 formatted timestamps?

I found
  void time_to_tm(time_t totalsecs, int offset, struct tm *result)
in include/linux/time.h around line 200, which comes close, but the
other way round would be more interesting.

regards
  Dan

Some questions in v6_copy_user_highpage_aliasing

Gavin Guo — 2012-05-08T03:40:44

Hi all,

I have traced v6_copy_user_highpage_aliasing in arch/arm/mm/copypage-v6.c
and found some questions.

 72 /*
 73  * Copy the page, taking account of the cache colour.
 74  */
 75 static void v6_copy_user_highpage_aliasing(struct page *to,
 76         struct page *from, unsigned long vaddr)
 77 {
 78         unsigned int offset = CACHE_COLOUR(vaddr);
 79         unsigned long kfrom, kto;
 80

I think the following statement is to solve aliasing problem that
kernel & user address map to the same physical frame. When
the kernel mapping is dirty, writing back is needed before the copy_page()
is used. Because the color bit of user space address & kernel one
may be difference which cause inconsistency. Now, the problem is
what is the scenario of dirty cache. When does the PG_dcache_dirty
set ? In normal copy-on-write case, I think the if clause will be false.

 81         if (test_and_clear_bit(PG_dcache_dirty, &from->flags))
 82                 __flush_dcache_page(page_mapping(from), from);
 83

The probl

Timer drivers using clocksource and clockevents api

Bahadir Balban — 2012-04-09T21:01:16

Hello,

I wrote a virtual timer for a virtual platform. I do not actually have a
timer hardware device, but I have a periodic irq that I can use and I
know the period which every irq occurs. 

The result I get is a working clock source, but it is slow. The driver
is not %100 right as I have little knowledge of clocksource and
clockevents API. Can you help in spotting issues in the below driver?

All the numbers are made up :) I would appreciate guidance for what to
use on clkrate, cycle value, and any other api parameters.

Thanks in advance,
Bahadir

Invitation to connect on LinkedIn

Carter Cheng via LinkedIn — 2012-02-28T18:05:27

LinkedIn
------------




    Carter Cheng requested to add you as a connection on LinkedIn:
  

------------------------------------------

Greg,

I'd like to add you to my professional network on LinkedIn.

- Carter

Accept invitation from Carter Cheng
http://www.linkedin.com/e/-13f7ym-gz78yq20-a/gUfpE6MtuEhIxgEzB5uqY5tHupjIxRpxsUQoK7Qq/blk/I179014284_75/1BpC5vrmRLoRZcjkkZt5YCpnlOt3RApnhMpmdzgmhxrSNBszYRdRYQe38Qcj0VdP59bSV5hCVTt3xIbPsRc3gNd38McjoLrCBxbOYWrSlI/EML_comm_afe/?hs=false&tok=0rSLxfV1vZml81

View invitation from Carter Cheng
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Invitation to connect on LinkedIn

Frankie onuonga via LinkedIn — 2012-01-21T18:57:07

LinkedIn
------------




    Frankie onuonga requested to add you as a connection on LinkedIn:
  

------------------------------------------

Greg,

I'd like to add you to my professional network on LinkedIn.

- Frankie

Accept invitation from Frankie onuonga
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Re: tcp/ip

Johan Nestaas — 2012-01-16T06:19:17

Thank you everyone!
I will definitely read some of those suggestions before opening the source
again.

Thanks,
Johan

2012/1/15 François-Frédéric Ozog <ff< at >ozog.com>

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Re: Kernel-mentors Digest, Vol 72, Issue 2

sanjeev — 2012-01-16T06:11:19

hi john,

Please follow the book "


   1. *TCP/IP Illustrated, Volume 3: TCP for Transactions, HTTP, NNTP, and
   the UNIX Domain Protocols <http://www.kohala.com/start/tcpipiv3.html>*,
   Addison-Wesley, 1996.

It will help you a lot.

Thanks & Regards

Sanjeev

On Sun, Jan 15, 2012 at 11:30 PM, <kernel-mentors-request< at >selenic.com>wrote:

RE: tcp/ip

François-Frédéric Ozog — 2012-01-15T21:39:38

I strongly suggest you read « Understanding Linux Network Internals.

 

The networking stack as a separate, huge beast. You could be a skilled disk
driver writer and still have absolutely no clue how the stack works. Another
mega beast is USB

 

Trying to understand it from source code is NOT an option, unless you have a
few years ;-)

 

 

De : kernel-mentors-bounces< at >selenic.com
[mailto:kernel-mentors-bounces< at >selenic.com] De la part de Johan Nestaas
Envoyé : dimanche 15 janvier 2012 11:36
À : kernel-mentors< at >selenic.com
Objet : tcp/ip

 

Hi,


Sorry if this is too newb of a question for the mailing list, but I tried
the kernelnewbies irc chat and no one was responding. Maybe someone could
direct me to a proper mailing list if this isn't the right place.

 

I've been trying to follow the latest kernel source of the tcp/ip stack but
I feel overwhelmed and I don't know the best file to start reading from.
Right now I'm reading linux/net/ipv4/af_inet.c but I have a feeling this is
not the best place

Re: tcp/ip

Steve Iribarne — 2012-01-15T19:12:55

printk is your friend!  Just start putting it in places once you read those articles and you'll start to get it

-stv


On Jan 15, 2012, at 3:33, sumeet gandhare <sumeetgandhare< at >gmail.com> wrote:

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Re: tcp/ip

sumeet gandhare — 2012-01-15T11:33:35

have a look at this link on kernelnewbies

http://kernelnewbies.org/Networking?action=AttachFile&do=get&target=hacking_the_wholism_of_linux_net.txt

HTH,

Regards,
Sumeet

On Sun, Jan 15, 2012 at 4:05 PM, Johan Nestaas <johannestaas< at >gmail.com>wrote:

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tcp/ip

Johan Nestaas — 2012-01-15T10:35:43

Hi,

Sorry if this is too newb of a question for the mailing list, but I tried
the kernelnewbies irc chat and no one was responding. Maybe someone could
direct me to a proper mailing list if this isn't the right place.

I've been trying to follow the latest kernel source of the tcp/ip stack but
I feel overwhelmed and I don't know the best file to start reading from.
Right now I'm reading linux/net/ipv4/af_inet.c but I have a feeling this is
not the best place to start. Does anyone have any suggestions? This would
basically be my start to analyzing the kernel source and operating system
data structures, outside of an Operating Systems class I took a semester
ago.

Thanks,
Johan
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One question about the kernel timer

Wizard — 2012-01-14T15:49:29

All

I am reading this code in kernel/timer.
my thought is for most of the timer in tv->vec, after cascade they
will stay in the same level.
Am I right?

1014static int cascade(struct tvec_base *base, struct tvec *tv, int index)
1015{
1016        /* cascade all the timers from tv up one level */
1017        struct timer_list *timer, *tmp;
1018        struct list_head tv_list;
1019
1020        list_replace_init(tv->vec + index, &tv_list);
1021
1022        /*
1023         * We are removing _all_ timers from the list, so we
1024         * don't have to detach them individually.
1025         */
1026        list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
1027                BUG_ON(tbase_get_base(timer->base) != base);
1028                internal_add_timer(base, timer);
1029        }
1030
1031        return index;
1032}

I think this function is trying to move some of the timer to another level.
Since the internal_add_timer() will calculate the hash number based on
the timer->expire,
so I guess for the ti

Should I generate inode numbers?

Dan Luedtke — 2011-12-13T17:43:29

Hello everyone,

I am thinking about a concept for a filesystem (read: kernel-module),
and when studying the sources I found in in include/linux/fs.h

 751 struct inode {
 ...
 771         /* Stat data, not accessed from path walking */
 772         unsigned long           i_ino;

Source: http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=blob;f=include/linux/fs.h;h=057434af2b900e18745b375b109e52ef03a9c6c0;hb=HEAD#l772

I want to use the blocknumber as inode number to
-keep the code simple
-avoid collisions and
-always know which block of a device an inode can be found in.

When I would my code like intended, and it would be compiled on a 32
bit machine, then unsigned long would be 32 bit. That would cause some
trouble when mounting partitions with more than 2^32 blocks, wouldn't
it?

So, as long as i_ino is not 64 bit (which was already discussed years
ago by some ext4 developers I think), what should I do? Should I
generate inode numbers (e.g. by incrementing a "global" variable) and
check for

advice on next step

Frankie Onuong'a — 2011-12-02T10:15:59


Hi guys,
I would like to kindly ask for an extension on the time I gave.I came across a book :
Understanding the Linux Kernel by Daniel P Bovet and Marco Cesati.
I believe to further help i need to go from page on to the end of it.I have already started but i believe with another two weeks all should be on my finger tips.
Thanks again to : vijaitm< at >gmail.com and Greg for the direction.
keep well.

frankie
La presente comunicación tiene carácter confidencial y es para el exclusivo uso del destinatario indicado en la misma. Si Ud. no es el destinatario indicado, le informamos que cualquier forma de distribución, reproducción o uso de esta comunicación y/o de la información contenida en la misma están estrictamente prohibidos por la ley. Si Ud. ha recibido esta comunicación por error, por favor, notifíquelo inmediatamente al remitente contestando a este mensaje y proceda a continuación a destruirlo. Gracias por su colaboración.This communication contains confidential information. It is for the exclu

Re: What should I do when I cant get any response to my patch

Greg KH — 2011-11-27T09:29:13

Not really.


I don't really know, try asking the ARM developers about the platform
stuff.

greg k-h

Re: What should I do when I cant get any response to my patch

Denis Kuzmenko — 2011-11-26T21:33:01

I've also expanded that list with few people who I saw linux-kernel list
working on same subarch (in my current understanding of that word). Is
there any other way to find people interested in my patch?


I just wanted to clarify the meaning of subarch.

I have s3c2440 core, which is a part of s3c24xx family which is a part
of Samsung-SoC family which belongs to ARM arch.
So in my case:
ARM is an arch,
Samsung-SoC is a subarch,
s3c24xxis a sub-subarch (or a platform?)

Is my understanding right?

Re: What should I do when I cant get any response to my patch

Greg KH — 2011-11-26T19:55:27

Yes, it's a great start, but don't let it substitute for common sense :)


I don't know, you should know best based on the patch location and what
hardware is affected here.

good luck,

greg k-h

RE: advice on next step

Frankie Onuong'a — 2011-11-26T19:57:23

Hi.thanks for the advice.I will be sure to remind myself these.please give me about two weeks as I am also in the middle of my end year exams.
thanks,
frankie


La presente comunicación tiene carácter confidencial y es para el exclusivo uso del destinatario indicado en la misma. Si Ud. no es el destinatario indicado, le informamos que cualquier forma de distribución, reproducción o uso de esta comunicación y/o de la información contenida en la misma están estrictamente prohibidos por la ley. Si Ud. ha recibido esta comunicación por error, por favor, notifíquelo inmediatamente al remitente contestando a este mensaje y proceda a continuación a destruirlo. Gracias por su colaboración.This communication contains confidential information. It is for the exclusive use of the intended addressee. If you are not the intended addressee, please note that any form of distribution, copying or use of this communication or the information in it is strictly prohibited by law. If you have received this communicati

Re: What should I do when I cant get any response to my patch

Denis Kuzmenko — 2011-11-26T19:35:15

Hi Greg,

On 11/26/2011 05:19 PM, Greg KH wrote:

So getting recipients list from get_maintainer.pl output is not enough?
What is subarch? Is this a Samsung-SoC or some more specific (s3c, s5p)?


Thank you.

Re: What should I do when I cant get any response to my patch

Greg KH — 2011-11-26T15:19:17

Send it again, it's so small, I don't see why it wouldn't be accepted.


Please resend, to the maintainer of that file and cc: the subarch
maintainers as well.

Persistence is key.

greg k-h

What should I do when I cant get any response to my patch

Denis Kuzmenko — 2011-11-26T14:02:43

Hi Linux Mentors.

I've made a patch to add support of LCD W35i for Mini2440 board. Looks
like this is a new version of LCD which is supplied with all new boards.

First time I've posted that patch:

https://lkml.org/lkml/2011/6/13/345
https://lkml.org/lkml/2011/6/14/331

got comments and fixed all things required to be fixed.

I've tried to resend that patch in five months and now I can't get any
replies

https://lkml.org/lkml/2011/11/17/376

I've formed recipients list from the output of get_maintainer.pl script.
This looks like no one is interested in this feature being in mainline?

There is no way I can prove that this feature is needed by many users
but I've received a letter from someone googled W35i support with a
question on how to use that display with Linux.

So suggest me please what should I do next?

Should I email this path to Andrew Morton for inclusion in -mm three?
Or should i just periodically repost that waiting or someone got interested?