On WinCE 6, i am seeing excessive page thrashing because the default loader paging settings are very low. I cannot fix this at the OS level so i must fix it at the application level. My hope is to get my application out of the business of paging completely. Is this possible?
Referring to this, it may be: http://msdn.microsoft.com/en-us/library/ms933104.aspx
...but that may only be for device drivers on ROM. Anyone know more definitively?
The answer is yes. There are linker settings for this.
Related
I built a game in j2me and I have memory leak because from time to time I get out of memory exception, now I want to spot where this leak is coming from and I heard you can do it with sun's wireless tool kit. Can someone explain me exactly what is this wireless tool kit, how I install it and how to use it in-order to find memory leaks ? Thanks in advance !
After you download wtk,Go to \bin\utilsw.exe.Under Utilities you will see "Memory monitor".Here you can graphically view app memory/RAM usage.
I do not know oracle sdk 3.4, but in wtk2 memory monitor was only partially useful for finding memory leaks, because it only shows how many (and which) objects are live, but not where they are referenced from. So it takes a review of corresponding piece of code.
Memory leaks are easier to find with a java profiler. You need to get one that suits you (I prefer YourKit, but it is commercial product with a trial period), modify emulator's command line in order to allow the profiler to connect (that should be covered by profiler's documentation, it is basically about adding -agentlib or -Xrun... option) to it, and do actual profiling (every profiler comes with a guide of how to do it).
I have ARM-based device with linux on-board. Its very difficult to flash custom kernel for some reasons (uBoot cant load kernel via tftp or something else)
I need to test my custom kernel.
So, idea is - replace kernel in memory. How do you think, is it possible?
Tell me any suggestions please.
Take a look at this link
It's for a project called Ksplice that allows one to patch a running kernel.
At one point this code was open, but Oracle bought it... So they may have closed it up and made it cost money. If that's the case, look around and see if you can find the formerly open code in the wild...
I am trying to enable Hyper-V in my local machine running Windows 8 Enterprise Ed 64-bit. I checked and my hardware is SLAT-compatible, the option in BIOS is turned on. I did several cold boot but the Hyper-V platform option still remains grayed out. I hope someone can help me since all the blogs/forums that seems to address this issue did not solve the issue for me.
If you hover your mouse over the Hyper-V item in the Optional Features list, it will tell you why it's disabled.
Otherwise, you can run MSINFO32.EXE and the System Summary panel will list the features required for Hyper-V and whether or not those features have been detected on your system.
Also, you said you've cold-booted the system a few times. This might sound stupid, but shut your system down and unplug it for a few minutes to make sure it's actually off before plugging it in and turning it on again. I've never seen a system where I had to do this, but I know other people who have.
Turn on Data Exeuction Prevention ?
Control panel - System - System Properties -Data Exeuction Prevention
I've spent a lot of time developing an operating system and working on my low level boot loader. But now I want to take some time off my operating system while not leaving the low-level environment and doing something involving security.
So I chose to build my own standard password utility following the pre-boot authentication scheme. Since I want the software to be at least a little portable I want it to use as little external support as is possible. I figured that I'd be best if I somehow managed to 'hook' into the bios somewhere between the self checks and the int 19 bootstrap from within a running real mode OS.
However finding information on how to modify the bios code proved to be impossible. I've found nothing on how to achieve the before mentioned. I have only found pages describing how to flash your bios.
Does anyone know how I can read/write bios code? Or can someone provide links to pages that describe this?
I know that it's not only possible to brick my device but it is also likely, I'm aware of the risk and willing to take it.
Pinczakko's articles on BIOS reverse engineering are a great place to start looking at this. There was also a book published by the same author but it is now out of print.
I'm not sure if this approach is the best approach towards a secure boot, but the articles on this site are very detailed and should point you towards a method for modifying your BIOS firmware.
I'm not really sure what you are trying to achieve, but:
The BIOS is completely hardware specific - each manufacturer will have their own mechanism for updating / flashing BIOS and so trying to come up with a portable mechanism for updating a BIOS is destined for failure. For example when using Bochs you "update" the BIOS by specifying a different BIOS ROM image.
If you want to modifty / write your own BIOS then its going to be completely specific to that hardware. Your best bet would be to start with something like Bochs as its open source - as you can take a look at the source code for the BIOS (and easily test / debug it) you stand a reasonable chance of understanding the BIOS code and modifying it into something that works, however I suspect this isn't what you are trying to do.
Why not just perform this authentication as your OS boots? If you want to protect the data then you should encrypt it and require that the user supply log in / supply the decryption key on startup.
If you were thinking of working with "legacy" PC BIOS, I would dissuade you from trying for many of the reasons Justin mentioned: 1) legacy BIOS is PC vendor-specific; 2) it is closed source and proprietary; 3) there are no industry standards defining legacy BIOS interfaces for extending the system as you are trying to do.
On the other hand, if you have access to a UEFI-based BIOS PC, you may be able to write your own PEI/DXE driver(s) to implement such a feature. This will at least point you in the right direction:
http://sourceforge.net/apps/mediawiki/tianocore/index.php?title=Welcome
Intel Press book on the topic: Beyond BIOS
Regarding the practicality of read/writing the BIOS, you'll need to identify the SPI part containg the BIOS and get a ROM burner. The SPI part may or may not be socketed; if it is not socketed, you'll need a soldering iron and be able to create a socket/header for the part. You obviously do not want to embark on this project with your primary computer system. Perhaps you could find an older system or a reference board.
A linux machine freezes few hours after booting and running software (including custom drivers). I'm looking a method to debug such problem. Recently, there has been significant progress in Linux Kernel debugging techniques, hasn't it?
I kindly ask to share some experience on the topic.
If you can reproduce the problem inside a VM, there is indeed a fairly new (AFAIK) technique which might be useful: debugging the virtual machine from the host machine it runs on.
See for example this:
Debugging Linux Kernel in VMWare with Windows host
VMware Workstation 7 also enables a powerful technique that lets you record system execution deterministically and then replay it as desired, even backwards. So as soon as the system crashes you can go backwards and see what was happening then (and even try changing something and see if it still crashes). IIRC I read somewhere you can't do this and debug the kernel using VMware/gdb at the same time.
Obviously, you need a VMM for this. I don't know what VMM's other than VMware's VMM family support this, and I don't know if any free VMware versions support this. Likely not; one can't really expect a commercial company to give away everything for free. The trial version is 30 days.
If your custom drivers are for hardware inside the machine, then I suppose this probably won't work.
SystemTap seems to be to Linux what Dtrace is to Solaris .. however I find it rather hostile to use. Still, you may want to give it a try. NB: compile the kernel with debug info and spend some time with the kernel instrumentation hooks.
This is why so many are still using printk() after empirically narrowing a bug down to a specific module.
I'm not recommending it, just pointing out that it exists. I may not be smart enough to appreciate some underlying beauty .. I just write drivers for odd devices.
There are many and varied techniques depending on the sort of problems you want to debug. In your case the first question is "is the system really frozen?". You can enable the magic sysrq key and examine the system state at freeze and go from there.
Probably the most directly powerful method is to enable the kernel debugger and connect to it via a serial cable.
One option is to use Kprobes. A quick search on google will show you all the information you need. It isn't particularly hard to use. Kprobes was created by IBM I believe as a solution for kernel debugging. It is essentially a elaborate form of printk() however it allows you to handle any "breakpoints" you insert using handlers. It may be what you are looking for. All you need to do is write and 'insmod' a module into the kernel which will handle any "breakpoints" hit that you specify in the module.
Hope that can be a useful option...
How I debug this kind of bug, was to run my OS inside the VirtualBox, and compile the kernel with kgdb builtin. Then I setup a serial console on the VirtualBox so that I can gdb to the kernel inside the VirtualBox's OS via the serial console. Anytime the OS hang, just like magic sysrq key, I can enter ctrl-c on the gdb to stop and understand the kernel at that point in time.
Normally kernel stack tracing is just too difficult to pinpoint the culprit process, so the best way I think is still generic "top" command, just looking at the application logs to see what are the cause of hanging - this will need a reboot to see the log of course.