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Re: Kernelnewbies Digest, Vol 71, Issue 26
by Laurence Rochfort Oct. 27, 2016

Oct. 27, 2016

The BBC Micro which was 6502 based had an add on that let you connect a Z80 straight onto the same bus. Different regards "operating system" I know, but it has been tried before. On Fri, 21 Oct 2016, 17:00 , <kernelnewbies-request(a)kernelnewbies.org> wrote: > Send Kernelnewbies mailing list submissions to > kernelnewbies(a)kernelnewbies.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > or, via email, send a message with subject or body 'help' to > kernelnewbies-request(a)kernelnewbies.org > > You can reach the person managing the list at > kernelnewbies-owner(a)kernelnewbies.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Kernelnewbies digest..." > > > Today's Topics: > > 1. Is that possible to implement a single machine with > heterogeneous architecture. (Douglas Su) > 2. Re: Is that possible to implement a single machine with > heterogeneous architecture. (Felix Bytow) > 3. Re: Is that possible to implement a single machine with > heterogeneous architecture. (Valdis.Kletnieks(a)vt.edu) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 21 Oct 2016 03:10:28 +0000 > From: Douglas Su <d0u9.su(a)outlook.com> > Subject: Is that possible to implement a single machine with > heterogeneous architecture. > To: kernelnewbies <kernelnewbies(a)kernelnewbies.org> > Message-ID: > < > SN1PR04MB2096827D49CA8F766DA1392EECD40(a)SN1PR04MB2096.namprd04.prod.outlook.com > > > > Content-Type: text/plain; charset="iso-8859-1" > > Hello everyone, > > > Is that possible to install multiple CPUs which have different > architecture on a single machine? For example, on a single machine with two > different cpu sockets for X86 and MIPS cpu respectively, and these two cpus > are inter-connected with some sorts of bus (PCI or other advanced buses). > > > If it is possible, Is this machine still SMP? What will lscpu (or cat > /proc/cpuinfo) dump? > > > Thx! >

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NAT with unique egress port
by Rui Santos Oct. 27, 2016

Oct. 27, 2016

Hi all, I'm currently using NAT to provide Basic address translation from private to public IP's. However, linux kernel uses both destination IP and Port as part of it's NAT mapping process. This way (client1 and client2 are on the same internal network): - if client1 connects to server1 using source port X, the NAT will be mapped: client1IP:SourcePortX -> server1IP:SourcePortX; - if client2 then connects to server2 using source port X, the NAT will be mapped: client2IP:SourcePortX -> server2IP:SourcePortX. Basically, SourcePortX is used on both mappings for client1 and client2. But, if client2 tries to connect do server1 instead, using the same source port X, the NAT will be mapped: client2IP:SourcePortX -> server2IP:SourcePortY SourcePortY will be an available (randomly generated?) ephemeral port. My goal is to force this behavior on all outgoing connections. This way I would get a unique egress port mapping to an internal IP:Port in a specific point in time: - if client1 connects to server1 using source port X, the NAT will be mapped: client1IP:SourcePortX -> server1IP:SourcePortX; - if client2 then connects to server2 using source port X, the NAT will be mapped: client2IP:SourcePortX -> server2IP:SourcePortY. SourcePortY will be an available (randomly generated?) ephemeral port. I am aware that this will imply a concurrent NAT connections limit, equal to the ephemeral port range, per egress IP. Is there any way I can accomplish this kind of behaviour? Thanks for all your help, -- Rui Santos Veni, Vidi, Linux

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Latest kernel documentation tree
by Jai Krishna Oct. 26, 2016

Oct. 26, 2016

Hello, Im trying to follow the documentation work of converting to Sphinx etc that Jon, Mauro and others are doing ( inferring from the patches coming into kernel-docs@ ). Id like to be able to pull and build the Sphinx based docs, learn and possibly even contribute (wish, wish...). However, Im stuck on a very mundane thing. Im not quite sure which tree has the latest sources. I looked at kernel/kernel-docs.git on git.kernel.org but that seems stale. Im not quite sure if its kernel/gregkh/staging.git. Can someone kindly point me to the correct tree that has the latest sources of Sphinx docs? Thanks Jai

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Stale pages: FAQ/VariousKernelTrees OutreachyfirstpatchSetup
by Duncan Oct. 26, 2016

Oct. 26, 2016

[I'm not subscribed. Please CC me on followups.] Two points: 1) The FAQ/VariousKernelTrees page is embarrassingly outdated with a last update in 2007 and still referring to 2.6.* as current, while both it and 3.x are arguably now historical status. 2) I actually followed a link to kernelnewbies from kernel.org, while looking for current recommendations on /secure/ git remote URLs -- it occurred to me that I really should replace my current git:// fetches with something more secure, and I wondered what was current best-practice. While rather less technical than most of the material covered here, it seems neither kernel.org nor kernelnewbies.org has an immediately obvious (including in the FAQ, at least that's immediately obvious) link to a discussion of something so basic. kernel.org does list https://git.kernel.org , but there's no real discussion or recommendation of https vs. less secure protocols, pointing out that git:// (apparently) isn't secure or indication of whether the obvious gits:// will or won't work, and no indication that the just as prominently listed rsync:// url (apparently) isn't secure either, let alone any distinction in terms of what's available, releases vs live git tree, between the three listings there (http/git/rsync). kernelnewbies.org does appear to have some basic instructions on the OutreachyfirstpatchSetup page, but there's three problems with that: a) Outreachy isn't immediately obvious as where one should look for this. I thought the front page outreachy link was to some organizational blurb (for all I know it is as I followed a more convoluted path to the above page), not a howto, and in terms of the patches part, I already know how to apply patches but am more personal systems admin and git kernel builder/tester/bug-reporter than coder so don't really generate patches for more than private use, and simply wanted information on updating my git pull URLs to something more secure. b) The staging tree might not be the best example for true kernel git sources newbies, mainline is arguably a better one. c) The example again appears dated and insecure, using the git:// protocol that the git-fetch manpage's GIT URLS discussion specifically warns should be used with caution on unsecured networks like the general internet, because it does no authentication and is /not/ secured. FWIW, I'm going with the https://git.kernel.org link for now, but thought it worth the trouble to at least post this as someone who can do something about it definitely needs to update (or delete if not considered with the trouble to update) those two pages at least, and possibly provide a more obvious basic mainline kernel git setup link on the front page, as well. Because right now they're just adding to the huge pile of outdated and now actively security-dangerous advice about Linux out there on the net. -- Duncan - No HTML messages please; they are filtered as spam. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman

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Why I can't find PCIe Device
by Muni Sekhar Oct. 25, 2016

Oct. 25, 2016

Hi All, I am using Adlink COM Express Type 2 module and American Megatrends Inc BIOS. I put the AMD Radeon Graphics card in the PCIe slot, but it’s not detected(lspci does not show this device) Any idea, what might be the reason for not detecting the PCIe graphics card? Is there any BIOS settings related to PCIe needs to be checked? -- Thanks, Sekhar

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What subsystem!?
by Daniel. Oct. 25, 2016

Oct. 25, 2016

Hi everybody, I've been studying linux for some time now. I still see my self as an begginer, but that's not a bad thing. I struggling to decide what subsystem to focus right know. I have three options and would like to know what people think about, since listening (or reading) other people aways help me to decide. My options are: i. Memory ii. Network iii. Filesystems / Disk cache Today I'm working on embedded market and have a crush on ARM architecture. I have absolute no knowledge on (i), some fundations (in userspace) on (ii) and nothing but mkfs experience on (iii). LoL. The second question is: What are the (market) applications of these expertise? I know that (ii) will be huge part ot IoT and IIoT. And the (iii) can be used on database tunning for example. (i) seem just f******* cool to me. When I say (market) please, do not get me wrong. The jobs on kernel are not popping out (especially on Brazil) like the Java & Big Data ones, I still have to eat, but I'm not willing to move from my passions(kernel-dev) for money. Thanks in advance and regards to everybody! -- "Do or do not. There is no try" Yoda Master

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Device Tree
by Madhu K Oct. 25, 2016

Oct. 25, 2016

Hi All, This is to understand how Device tree works in linux kernel. If in case Device tree is not there, where and how to pass the hardware information to the linux kernel. Does all embedded systems contains Device tree? Regards, Madhu

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dirty page throttling?
by Raymond Jennings Oct. 25, 2016

Oct. 25, 2016

I was told that it had something to do with balance_dirty_pages(), but how do I allow my system to dirty as much data as it wants to? I'm running a world simulation with a lot of I/O churn, and I'm trying to get my system to 1. Let it dirty as much data as it wants to, even booting out anon or filecache to do so up to /proc/sys/vm/dirty_ratio 2. When it wants to writeback, don't throttle how much gets moved from Dirty to Writeback, but basically dump the entire load in one go and let the I/O scheduler digest it.

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Is that possible to implement a single machine with heterogeneous architecture.
by Douglas Su Oct. 21, 2016

Oct. 21, 2016

Hello everyone, Is that possible to install multiple CPUs which have different architecture on a single machine? For example, on a single machine with two different cpu sockets for X86 and MIPS cpu respectively, and these two cpus are inter-connected with some sorts of bus (PCI or other advanced buses). If it is possible, Is this machine still SMP? What will lscpu (or cat /proc/cpuinfo) dump? Thx!

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QEMU?
by Kenneth Adam Miller Oct. 19, 2016

Oct. 19, 2016

So, we can use qemu within our development system here, but the problem is we have something that is a bit specialized in that the machines talk to one another over a special interface. It's a bit like named pipes, and to our applications, named pipes are a sufficient interface to test over. In any case, I was wondering, does anybody know of a way to share memory between two QEMU instances? Or even to communicate between two instances?

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