Questions Tagged With kernel-space

how to redirect the output of serial console (e.g. /dev/ttyS0) to a buffer or file

cremeplawen — Mon, 01 Jul 2013 10:27:31 -0400

Is it possible to pipe serial console output to a file or a buffer or some virtual or pseudo device (in /dev)? The Kernel command line has in startup at this point "console=null,115200". (Normally it has "console=ttyS0,115200" - my requirement is: if "console=null,115200", should the output go to some other place than ttyS0, e.g. a virtual or pseudo device or to a file/buffer)

Maybe somebody know if there is good solution available?

Thanks a lot in advance!

using system calls (cwd) in kernel space

bhushiman — Mon, 27 Feb 2012 06:01:13 -0500

i am using the getcwd() function to get the current path. this works fine in the user space but when used in a kernel module gives the error as implicit declaration of the function. i have tried using sys_getcwd which was defined in the implementation of getcwd(in linux/unistd.h) but then there is an error implicit declaration of getcwd Plzz let me know how to use the same.. plz help its a little urgent.. thank you

Memory allocation in Linux

thinku — Sun, 02 May 2010 11:14:14 -0400

I got a doubt with memory allocation in Linux

I am having 256 MB of RAM in my portable player and the linux kernel is given with parameter "MEM=110M" while booting,

Can any one explain what does that mean

Is it a ...

1) 110 M is given for Kernel memory and remaining 146 is for user-space memory

or 2) 110M is given for kernel & user-space and remaining can be configured as per requirement (may be... say, driver memory)

Also, when i start a application that has many malloc in it., at some point the malloc() function returns null., whereas i parallely checking through Telnet for the "free memory space" through "free" cmd, it returns 39 MB as unused (ie., free)

I am little confused now (may be i am not knowing the memory partitions), can any one explain on this

Thanks in advance

Thanks Jlliagre, My free observation is here

> #free
>         total   used   free   shared   buffers  
    Mem: 106428   66560  39868   0        5240 
> #

" Jlliagre --- Malloc is allocating virtual memory while free is displaying RAM and SWAP usage "

fine, then does it mean that virtual memory for a process is fixed amount so that other processes will also get memory, instead of putting other processes running out of memory.

my concern is even-though free shows 39868 KB, it fails on malloc() of 2.5 MB