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Search found 8 results on 1 pages for 'ring0'.

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  • Doubts in System call mechanism in linux

    - by bala1486
    We transit from ring3 to ring0 using 'int' or the new 'syscall/sysenter' instruction. Does that mean that the page tables and other stuffs that needs to be modified for the kernel is automatically done by the 'int' instruction or the interrupt handler for the 'int 0x80' will do the required stuff and jump to the respective system call. Also when returning from a system call, we again need to go to user space. For this we need to know the instruction address in the user space to continue the user application. Where is that address stored. Does the 'ret' instruction automatically changes the ring from ring3 to ring0 or where/how this ring changing mechanism takes place? Then, i read that changing from ring3 to ring0 is not as costly as changing from ring0 to ring3. Why is this so?? Thanks, Bala

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  • How to copy a DVD [closed]

    - by ring0
    I was offered a couple of DVDs from abroad that cannot be played on my player due to region filtering. So I tried k9copy to copy the DVD (it removes the region automatically). But for some reasons the copy does not work well (followed the instructions from here but the generated ISO file does not work / not even in media player - additionally there are many bugs in k9copy 2.3.5 (latest from Ubuntu) showing that it is not a reliable software, at least not on Gnome...). My question is simple: how to copy a DVD on Ubuntu, the copy/ISO being as close to the original, but without the region code.

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  • Postfix: change sender in queued messages

    - by ring0
    Following a complete re-installation we got a problem with the configuration: the sender address was wrong and some recipients (mail servers) rejected them. So there is a bunch of mails stuck in the Postfix queue. Ideally, a change of the sender address directly in the queued mails, and then flushing the queue would be optimal. I tried this answer that addresses this very problem. But messages don't seem to be easily modifiable in the version I have (2.11.0). For instance there is no /var/spool/mqueue dir, but, instead, /var/spool/postfix/... active bounce corrupt defer deferred dev etc flush hold incoming lib maildrop pid private public saved trace usr and the dir of interest is deferred. I tried to modify a few files there changing the wrong domain with the correct one (and was careful to ensure only those were changed). But then, those mails were moved to corrupt, meaning that a simple text change doesn't seem to work (done with vi). Any other cleaner way to change the sender in queued mails?

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  • Strange Upload Problem on Hyper-V

    - by Ring0
    Hi, This one is driving me totally nuts. I have being trying to upload a file to www.virustotal.com (its a harmless exe I have since found out - DiskWipe.exe from diskwipe.org). Using IE8. From Win 7 and Win 2008 R2 Datacenter (which I select to boot from vhd's) onto my main machine hardware, and also on another Win 7 PC elsewhere on my network, when I upload the file to virustotal.com it works perfectly. So, using my native NIC's everything is fine. Using another machine also perfect. Right. OK, from my boot menu the default is my main development machine - the one I'm typing on now. This runs on the metal and has Hyper-V role and I have some guests. All guests are not running. Amazingly, from my console (root partition to be exact) or any guest OS 2003 /XP / 2008 R2 etc. My upload to virustotal.com slows at 32% then HANGS at 38.something% & never finishes!! Here is the kicker. I have another box (my main server) running Hyper-V on the metal and three live guests. Identical H/W to my main dev machine in another room. (Except OS is Datacenter - Mine is Enterprise). If I try and upload from its bare metal console or any guest this file to virustotal.com using IE8 it stops exactly in the same place!! As for "steps I have tried etc." are kind-of blown out of the water as my server box is doing the precise same thing as the machine in my room here. OK, comonalities: Mobo: Gigabyte GA-X58-UD5, 12GB Kingston RAM, Corei7 920 4 cores hyperthreading = 8 & Realtek RTL8168D/8111D Family PCI-E Gigabit Ethernet NIC's. All 3 machines have this same motherboard - revision F11 Bios, all have 12GB RAM, all have the Realtek Nic's. All x64 by the way as I mentioned before I have a Win 7 box also with the UD5 m/Board, 12 GB RAM - bit of an overkill. :-) All these machines when NOT running Hyper-V can upload this file. Perhaps you may like to try it on a Hyepr-v (2008 R2) yourselves with IE8 and the desktop experience is on. See if it works or fails for you. Root OS or any guest. So, looking like its the NIC + Hyper-V = Cannot upload this file (any file I must add.) Realtek Nic is Ver 7.002.1125.2008. Using IE8 I see in the nic settings there are the usual parameters for Jumbo frames / Checksum offloading etc. several others. Should I fiddle with these? I ran Netmon 3.3 in a guest and the TCP session halted as the upload failed. I suppose I could study that further. I dont have Netmon on the root partition machine (yet)! All OS's fully patched - including todays defender files. My box running Office 2007 - but identical server in another room is not. Also, if I fire up a VPN to a distant client and do the upload it works! Of course its a different network path. Suggestions welcome please. If I left out anything important - please yell at me. Many Thanks,

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  • CSS overflow detection in JavaScript

    - by ring0
    In order to display a line of text (like in a forum), and end that line with "..." if the text would overflow the line (not truncating using the CSS overflow property), there are a number of ways. I'm still seeking the best solution. For instance, Adding in CSS a "..." as a background-image is a possibility, but it would appear all the time, and this is not a good solution. Some sites just count the characters and if over - say - 100, truncates the string to keep only 100 (or 97) chars and add a "..." at the end. But fonts are usually not proportional, so the result is not pretty. For instance the space - in pixels - taken by "AAA" and "iii" is clearly different "AAA" and "iii" via a proportional font have the same width There is another idea to get the exact size in pixels of the string: create in Javascript a DIV insert the text in it (via innerHTML for instance) measure the width (via .offsetWidth) which is not implemented yet. However, I wonder if there could be any browser compatibility problem? Did any one tried this solution? Other recommendations would be welcome.

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  • Java consistent synchronization

    - by ring0
    We are facing the following problem in a Spring service, in a multi-threaded environment: three lists are freely and independently accessed for Read once in a while (every 5 minutes), they are all updated to new values. There are some dependencies between the lists, making that, for instance, the third one should not be read while the second one is being updated and the first one already has new values ; that would break the three lists consistency. My initial idea is to make a container object having the three lists as properties. Then the synchronization would be first on that object, then one by one on each of the three lists. Some code is worth a thousands words... so here is a draft private class Sync { final List<Something> a = Collections.synchronizedList(new ArrayList<Something>()); final List<Something> b = Collections.synchronizedList(new ArrayList<Something>()); final List<Something> c = Collections.synchronizedList(new ArrayList<Something>()); } private Sync _sync = new Sync(); ... void updateRunOnceEveryFiveMinutes() { final List<Something> newa = new ArrayList<Something>(); final List<Something> newb = new ArrayList<Something>(); final List<Something> newc = new ArrayList<Something>(); ...building newa, newb and newc... synchronized(_sync) { synchronized(_sync.a) { _synch.a.clear(); _synch.a.addAll(newa); } synchronized(_sync.b) { ...same with newb... } synchronized(_sync.c) { ...same with newc... } } // Next is accessed by clients public List<Something> getListA() { return _sync.a; } public List<Something> getListB() { ...same with b... } public List<Something> getListC() { ...same with c... } The question would be, is this draft safe (no deadlock, data consistency)? would you have a better implementation suggestion for that specific problem? update Changed the order of _sync synchronization and newa... building. Thanks

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  • User to kernel mode big picture?

    - by fsdfa
    I've to implement a char device, a LKM. I know some basics about OS, but I feel I don't have the big picture. In a C programm, when I call a syscall what I think it happens is that the CPU is changed to ring0, then goes to the syscall vector and jumps to a kernel memmory space function that handle it. (I think that it does int 0x80 and in eax is the offset of the syscall vector, not sure). Then, I'm in the syscall itself, but I guess that for the kernel is the same process that was before, only that it is in kernel mode, I mean the current PCB is the process that called the syscall. So far... so good?, correct me if something is wrong. Others questions... how can I write/read in process memory?. If in the syscall handler I refer to address, say, 0xbfffffff. What it means that address? physical one? Some virtual kernel one?

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