how to perform floating point operations in linux kernel?
location: linuxquestions.com - date: April 7, 2011
one of interview question was how to perform floating point operations in kernel?
i answered that its impossible to perform floating point operations in kernel.but he is telling that its possible but with some feature to be added.can any body know about this perfectly????
thanks in advance
Use of floating point in the Linux kernel
location: linuxexchange.com - date: December 14, 2012
I am reading Robert Love's "Linux Kernel Development", and I came across the following passage:
No (Easy) Use of Floating Point
When a user-space process uses floating-point instructions, the kernel manages the transition from integer to floating point mode. What the kernel has to do when using floating-point instructions varies by architecture, but the kernel normally catches a trap and then initiates the transition from integer to floating point mode.
Unlike user-space, the kernel does not have the luxury of seamless support for floating point because it cannot easily trap itself. Using a floating point inside the kernel requires manually saving and restoring the floating point registers, among other possible chores. The short answer is: Don’t do it! Except in the rare cases, no floating-point operations are in the kernel.
I've never heard of these "integer" and "floating-point" modes. What exactly are they, and why are they needed? Does this distinction exist on ma
sigsuspend syscall causes floating point exception on ARM powered linux platform
location: linuxexchange.com - date: January 12, 2014
I am trying to run an application, which is originally from an ARM powered media center, on a QEMU VM. I also tried running it on my Raspberry Pi.
Unfortunately the application crashes when it tries to execute svc 0x009000b3 which is the OABI way of calling sigsuspend.
There are two, as far as I can tell, relevant instructions prior to the faulty call:
MOV R1, #8
MOV R0, SP
It is also worth mentioning that I successfully ran the busybox binary from the same media center on both the Qemu VM and the Pi.
I'd be happy for any idea for why the floating point exception could happen and how it can be avoided.
Floating point vs integer calculations on modern hardware
location: linuxexchange.com - date: May 9, 2012
I am doing some performance critical work in C++, and we are currently using integer calculations for problems that are inherently floating point because "its faster". This causes a whole lot of annoying problems and adds a lot of annoying code.
Now, I remember reading about how floating point calculations were so slow approximately circa the 386 days, where I believe (IIRC) that there was an optional co-proccessor. But surely nowadays with exponentially more complex and powerful CPUs it makes no difference in "speed" if doing floating point or integer calculation? Especially since the actual calculation time is tiny compared to something like causing a pipeline stall or fetching something from main memory?
I know the correct answer is to benchmark on the target hardware, what would be a good way to test this? I wrote two tiny C++ programs and compared their run time with "time" on Linux, but the actual run time is too variable (doesn't help I am running on a virtual server). Short o
Is there any way to make sure the floating point arithmetic result the same in both linux and windows
location: linuxexchange.com - date: May 6, 2013
My programe runs both in linux and windows, I have to make sure the floating point arithmetic get the same result in different OS.
Here is the code:
for (int i = 0; i < 100000; ++i)
float d_value = 10.0f / float(i);
float p_value = 0.01f * float(i) + 100.0f;
I use "g++ -m32 -c -static -g -O0 -ffloat-store" to build the code in linux.
I use "/fp:precise /O2" to build the code in windows with vs2005.
When I printf the "d_value" and the "p_value", the "d_value" is all the same both in linux and windows. But the "p_value" is different sometimes.
For exsample, print the "p_value" with hexadecimal format:
Why dose this happen?
My g++ version is
Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.5-8' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib
firefox 2.0 Floating Point Exception (core dumped) error on Ubuntu 6.10
location: linuxquestions.com - date: December 23, 2006
I've got a problem, firefox 2.0 suddenly won't start and give "Floating Point Exception (core dumped)" error.. i've tried running it on console with "firefox -safe-mode" but still i get the same error message..
I just don't get it.. firefox is running well before.. but now suddenly it wont start.
Please tell me what's wrong.. any help would be appriciated..
location: ubuntuforums.com - date: April 21, 2006
hi, a couple of my friends are going to buy new computers - either a desktop or laptop. both will probably buy something Linux compatible if they can get it easily, after my going on about it so much but, it doesn't seem that easy to just buy something you know will run Linux.
what's the easiest way to make sure something you are going to buy will run Linux? are there any good sites, or lists of pre-built desktops which are best to get? if i knew it would work and it was easy, i wouldn't mind putting something together, as i'll probably set them up anyway. BTW, i live in the UK. thanks.
Lenovo x121e i3 Linux Hardware Compatability
- date: December 13, 2011
This thread's aim is to provide a single up to date source for hardware compatibility for the Lenovo x121e (in particular the i3 variant) laptop. There are a number of detailed threads around that already cover the generals about the hardware, but don't specifically deal with Ubuntu/Linux support. Please post any updates or revisions and I will keep this initial post up to date
:~$ sudo dmidecode | grep Version
Version: Intel(R) Core(TM) i3-2367M CPU @ 1.40GHz
Version: 8QET53WW (1.14 )
Version: ThinkPad X121e
:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 11.10
:~$ uname -a
Linux racerx 3.0.0-14-generic #20-Ubuntu SMP Fri Oct 7 14:56:25 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
100% Supported (maybe with a patch)
A number of small bugs are present
UEFI Boot support needs to be disa
Toshiba Portege R700 / R705 Linux Hardware Compatibility Thread
location: ubuntuforums.com - date: August 10, 2010
Ive recently purchased a number of newly released Toshiba portege R700-15U business laptops. There was (and still is) very little linux related support information available due to it being a very new model so I have started to document the hardware compatibility under ubunutu 10.04. This is not intended to be a review or discussion of the laptop features, but a collation of compatibility info and fixes for this laptop under linux for owners or those looking to to buy one.
The R705 shares almost all the same components as the R700. It just lacks a number of features (bluetooth? fingerprint reader, express slot?, 5400rpm drive?) present on the R700 so there is no reason why it cant be tracked here also.
Feel free to post updates and I will keep this chart fresh.
Test OS: Ubuntu 10.04 Lucid Lynx amd64. Alternate installer, for encrypted LVM setup. Apart from that it was a standard install.
Test Firmware: Initial Release firmware
Works (maybe with a patch or fix)
A number o
Linux Hardware Diagnostic Software
location: ubuntuforums.com - date: May 8, 2008
Anyone out there know of a program I can install in Ubuntu (8.04) that will diagnose/troubleshoot hardware (Namely Hard Drive). I need to see if the drive has bad sectors, read it's smart status, etc. I need to check it's health in general. Any ideas?
Page: 1 2 3 4 5 6 7 8 9 10