Re: Maximum file size on JFFS2 file system

Hi,

> May i know what is the maximum file size that can be create on a JFFS2
> filesystem.
> I know eventhough this is not related to linux. I feel this is the right
> platform to ask

Theoretically according to this ([1]) the maximum supported file size should
be 4G. Anyhow, if you have the right setup you can give it a try :).

thanks,
Daniel.

[1] http://lxr.linux.no/#linux+v2.6.34/fs/jffs2/fs.c#L545

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reference to an undefined macro

Hi,

    The following definition of PMD_SHIFT is from
include/asm-i386/page.h of the kernel version 2.6.11

                     #define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)

But, there is no the definition of PMD_SHIFT at all in page.h, and
also no other header files included by it. How does this work?

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Re: reference to an undefined macro

Hi,

On Sun, Aug 1, 2010 at 3:33 PM, Parmenides <mobile.parmenides <at> gmail.com> wrote:
> Hi,
>
>    The following definition of PMD_SHIFT is from
> include/asm-i386/page.h of the kernel version 2.6.11
>
>                     #define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
>
> But, there is no the definition of PMD_SHIFT at all in page.h, and
> also no other header files included by it. How does this work?

I think you're supposed to #include <linux/mm.h>

This includes both asm/page.h and asm/pgtable.h, PMD_SHIFT is defined
by including asm/pgtable.h.

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Subject: why no different definitions of __pte

why no different definitions of __pte

Hi,

In include/asm-i386/page.h, the pte_t is defined like this

#ifdef CONFIG_X86_PAE
typedef struct { unsigned long pte_low, pte_high; } pte_t;
#else
typedef struct { unsigned long pte_low; } pte_t;
#endif

in other words, the pte_t is defined according to two situations
respectively. But, a subsequent macro

#define __pte(x) ((pte_t) { (x) } )

is unique yet.

In PAE's case, I think that the __pte should have two parameters that
doesn't exist at all. This really puzzle me.

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Re: why no different definitions of __pte

Documentation bug missing make image

Hey in the Linux Kernel Tester's Guide says that

Some distributions allow you to install a newly compiled kernel by running
# make install

as root from within the directory that contains the kernel sources.
Usually, however, you
will need to change the boot loader configuration file manually and if
you use lilo, you will
need to run /sbin/lilo to make the new kernel available to it.

    Moreover, if you use a modern distribution, you will need to
generate the initrd image

corresponding to the new kernel. The initrd images contain the kernel
modules that should
be loaded before the root filesystem is mounted as well as some
scripts and utilities that
should be executed before the kernel lets init run. To create the
initrd image for your
kernel and copy it to the system’s /boot directory, you can do:

# mkinitrd -k vmlinuz-<kernel_version> -i initrd-<kernel_version>

but in the ubuntu 10.04 you maight change the mkinitrd for the
update-initramfs comand

      The update-initramfs script manages your initramfs images on your local
       box.  It keeps track of  the  existing  initramfs  archives  in  /boot.
       There  are three modes of operation create, update or delete.  You must
       at least specify one of those modes.

       The initramfs is a gzipped cpio archive.   At  boot  time,  the  kernel
       unpacks  that archive into RAM disk, mounts and uses it as initial root
       file system. All finding of the  root  device  happens  in  this  early
       userspace.

In the FAQ help of kernel newbies doesn't tell about it

Hope it could  help to someone else it took me a while to understand
the reason of the problem.

Thanks for all

Victor Rodriguez

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How to query a kernel variable

Hi,
    I am reading the linux kernel of version 2.6.11. I want to query a
kernel variable named max_low_pfn while the kernel running. Is there
any means to achieve the goal? thx

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Re: Documentation bug missing make image

On Mon, Aug 2, 2010 at 21:46, Victor Rodriguez <vm.rod25 <at> gmail.com> wrote:
> Hey in the Linux Kernel Tester's Guide says that
>
> Some distributions allow you to install a newly compiled kernel by running
> # make install
>
> as root from within the directory that contains the kernel sources.
> Usually, however, you

.................. <snip>

Which problem actually? the "make install not really work"?

If that's your point, here's my understanding (since I almost never
use it anyway):
make install does things almost entirely automatic, like copying
bzImage and so on. However, it might not really suite your distro
condition and requirement.

Thus, the only way to make sure it works like it means to be, is by
doing everything by your own. Not so difficult actually.

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training: mulyaditraining.blogspot.com

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Re: How to query a kernel variable

Hi...

On Tue, Aug 3, 2010 at 00:47, Parmenides <mobile.parmenides <at> gmail.com> wrote:
> Hi,
>    I am reading the linux kernel of version 2.6.11. I want to query a
> kernel variable named max_low_pfn while the kernel running. Is there
> any means to achieve the goal? thx

Hi...once Robert Day and I discuss this kind of thing time ago.

Try to use gdb, ie gdb /path/to/your/vmlinux /proc/kcore. Then use
...uhm...IIRC p <variable name>

Beware that you need to rerun gdb (or something like that) to make
sure gdb read latest value.

And.....to make things easier, make sure you compile the kernel with
debug symbol included.

PS: Rob...your turn please?
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blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

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Re: SCTP Bundling Timeout value in linux

Hi,

Although I was aware that someone did reply your message:

http://www.spinics.net/lists/newbies/msg39728.html

But I think it could be wrong.   From here:

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ft_sctp2.html

Read till you came across the following line (which quote):

"The cumulative SACK (cumsack) timeout specifies the maximum time that
a SACK is delayed while waiting to bundle with data chunks."

Logically speaking, so long as u wait and bundle the bytes together,
you have to wait, and there should be a timeout period.

But under linux_kernel_source/net/sctp directory there are quite a few timeout:

typedef enum {
        SCTP_EVENT_TIMEOUT_NONE = 0,
        SCTP_EVENT_TIMEOUT_T1_COOKIE,
        SCTP_EVENT_TIMEOUT_T1_INIT,
        SCTP_EVENT_TIMEOUT_T2_SHUTDOWN,
        SCTP_EVENT_TIMEOUT_T3_RTX,
        SCTP_EVENT_TIMEOUT_T4_RTO,
        SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD,
        SCTP_EVENT_TIMEOUT_HEARTBEAT,
        SCTP_EVENT_TIMEOUT_SACK,
        SCTP_EVENT_TIMEOUT_AUTOCLOSE,
} sctp_event_timeout_t;

#define SCTP_EVENT_TIMEOUT_MAX          SCTP_EVENT_Txxxxxxx

and for TIMEOUT_SACK, it is (include/net/sctp/constants.h):

/* Delayed sack timer - 200ms */
#define SCTP_DEFAULT_TIMEOUT_SACK       (200)

On Mon, Jul 26, 2010 at 11:57 AM, Kiran P <kiran.kiranp <at> gmail.com> wrote:
> Hi,
> Could someone please tell me what is the SCTP bundling timeout value
> used in linux kernel?
>
> --
> Kiran
>
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