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How can I make dma_alloc to use the device's reserved memory?
by 김찬 Nov. 2, 2023

Nov. 2, 2023

Hi kernel experts, If some memory was reserved for a dma-able device using device tree's 'reserved-memory' property, if I do dma_alloc_coherent for the device, does it allocate memory in that reserved memory? I don't think so because dma_alloc_coherent works regardless of wether there is reserved memory for the device or not. Then how can I make the kernel reserve the dma memory from that reserved memory?  Thank you. Chan Kim

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How to switch driver from wireless extension to cfg/mac80211
by Philipp Hortmann Oct. 13, 2023

Oct. 13, 2023

Hi, after cutting away a lot of dead code from the rtl8192e I would like to understand the way forward to migrate the driver from wireless extension to cfg/mac80211. What is the best way forward to migrate the driver rtl8192e towards the drivers/net/wireless/realtek/rtlwifi/rtl8192* ? Does it have to be a hard cut? What to start with? - start to change the used structs towards ieee80211_hw? Thanks for your support. Bye Philipp

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help - macro arg reuse - fix ?
by jim.cromie＠gmail.com Oct. 13, 2023

Oct. 13, 2023

is there a simple fix for this ? -:451: CHECK:MACRO_ARG_REUSE: Macro argument reuse '_var' - possible side-effects? #451: FILE: include/linux/dynamic_debug.h:121: +#define DYNDBG_CLASSMAP_USE_(_var, _uname) \ + extern struct ddebug_class_map _var; \ + static struct ddebug_class_user __aligned(8) __used \ + __section("__dyndbg_class_users") _uname = { \ + .user_mod_name = KBUILD_MODNAME, \ + .map = &_var, \ }

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Why does kernel has different commandline options to disable Local APIC and I/O APIC?
by Mushahid Hussain Oct. 5, 2023

Oct. 5, 2023

I see that "noapic" and "nolapic" command line options are handled differently. "noapic" is handled in function "disable_ioapic_support()" which does following: ``` void disable_ioapic_support(void) { #ifdef CONFIG_PCI noioapicquirk = 1; noioapicreroute = -1; #endif skip_ioapic_setup = 1; } ``` however, nolapic is handled in a different function, which sets different variables: ``` /* * APIC command line parameters */ static int __init setup_disableapic(char *arg) { disable_apic = 1; setup_clear_cpu_cap(X86_FEATURE_APIC); return 0; } ``` I can also see that there's check to call "disable_ioapic_support" if local APIC is disabled: ``` /** * setup_local_APIC - setup the local APIC * * Used to setup local APIC while initializing BSP or bringin up APs. * Always called with preemption disabled. */ void setup_local_APIC(void) { int cpu = smp_processor_id(); unsigned int value, queued; int i, j, acked = 0; unsigned long long tsc = 0, ntsc; long long max_loops = cpu_khz ? cpu_khz : 1000000; if (cpu_has_tsc) rdtscll(tsc); if (disable_apic) { disable_ioapic_support(); return; } ``` but I don't see anywhere that kernel disabled Local APIC if "noapic" commandline option is passed. Shouldn't Local APIC be disabled as well, when there's a commandline option "noapic" to disable APIC? As per my understand, at least IOAPIC is needed for local APICs to function? If IO APIC is disabled, should Local APICs be also disabled? -- Mushahid Hussain

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ktypes vs. devices classes (struct class)
by Richard Oct. 2, 2023

Oct. 2, 2023

Hi all, Why do we have ktypes (struct kobj_type) AND device classes (struct class)? Don't they serve the same purpose (more or less) and it would be simpler, clearer and more KISS to only have one? Is this a historically grown thing or by design? Thanks, -- Richard

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Prefer strscpy over strcpy
by Jonathan Bergh Sept. 30, 2023

Sept. 30, 2023

hi there So this is a question about the common checkpatch warning I am sure (most) people have seen when runing checkpatch.pl over kernel code. In this particular example "driver_name": * In: vme_fake.c: static const char driver_name[] = "vme_fake": will always fit into vme_bridge->name: * In: vme_bridge.h: ... #define VMENAMSIZ 16 ... struct vme_bridge { ... char name[VMENAMSIZ]; ... } and yet in the __init function, the code uses: * vme_fake.c: strcpy(fake_bridge->name, driver_name); Is it (would not be) correct to use: * strscpy(fake_bridge->name, driver_name, sizeof(fake_bridge->name)); I cant see an issue, since driver_name is a const char[] and will always fit into fake_bridge->name but I wanted to check whether there might be some reason strcpy and not strscpy has been used? thanks in advance, regards Jon

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Re: Kernelnewbies Digest, Vol 154, Issue 14
by Michael Sept. 26, 2023

Sept. 26, 2023

Apologies on my last message, I didn't respond directly to Juro, Sorry Juro! On Mon, 25 Sept 2023 at 19:45, <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. Kernel improvements. (Juro Dobr?k) > 2. Re: [Question] dt bindings for BeagleConnect (Krzysztof Kozlowski) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 21 Sep 2023 04:47:17 +0200 > From: Juro Dobr?k <dobrik.juro(a)gmail.com> > To: kernelnewbies(a)kernelnewbies.org, freebsd-accessibility(a)freebsd.org > Subject: Kernel improvements. > Message-ID: > <CAAG+mdToFpmG48SC24i9ErMK9JExMMUzRjePwH= > YEnN0Kqv28g(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > In UNIX, everything is a file. I am here to make that a database. Yes, in > new system paradigm, everything is database entry, or active record. > > Kernel wide database should have defined bytecode of request possibilities, > along with pointer reference to query data. > > At some space in disk, there should be hardcoded in system kernel, that we > can only write there. It should be proposed to store deep logs. > > There should be guy for filtering logs, they should be more of serialized > entries in database than a line of text. If errors are serialized data, we > can check public errors repo for possible fix, with some data like new > keywords provided by user, but fix from database will be applied after > showing fix and affirmation by the user. > > Short range packet history of network also should be on write only space. > So we can raid out possible intruders and inspect packets. However with > master permission we could send packet out in invisible format or recieve > them like that, but it'll require finger prints, an absence of data will be > also locked. > > Now whole system is database, how do we pass data from database to process? > Simply passing read start and read end and call to refill bucket function. > We also pass metadata on how to decode such thing. > > When it comes to metadata, we live in world of machine learning, therefore > we can have something like system registry of data, and also software > packages, for packages, they may come in bundles, install should be > rollbackable by also setting context of packet when doing something else, > so like we can rollback install completely, install multiple versions > alongside itself, each packege should be working standalone or they can > come in preconfigured bundles. Whole configs along with data should then be > made installable. We should be able to define system instance that runs > under supervisor, which is copy on write copy with only data access we > selected. > > That thing can be solved like there's hook for copying for both sides. > > There should be manipulable path when writing to filesystem, consisting > only of compression with LCache fitting dictionary and encryption. Maybe > compress - encrypt will make it to hardware, with huge memory for > dictionary and not using only words but also patterns. > > Disks should have innovative raid approach, write in parallel and on no > writing copy to mirror. > > Virtual networks, tunnels and firewalls and redirection should be on one > section of system, with GUI that enables configuration of those properties > we need and also shows each process that uses network, so we can route > that. Or we can preconfigure this config on new instance, in that case > config is fixed with keyword, not the address itself. > > With online repository for errors, software, data, models, whole system > instances, we can also have this repositories peer to peer utilizing > blockchain consensus algorythm. > > System should have be possible configured 8n a way that it only boots with > key USB Stick. > > Storing of sensitive data on the system should be done in encrypted space > on hardisk that runs on main master instance and you should must give > permission for other instances to access that sensitive data for system for > being able to access passwords. > > Passwords entered in instance should be possibly better being exported with > it in sone cases. > > And I am talking about all passwords entered in webbrowser and also > elsewhere, it could even remember archive passwords on permission, also > passwords should be savable in instance config, but they could be make to > insert of ow on beggining of config > > Database of passwords can be stored in cloud firstly encrypted by symmetric > encryption. > > Each RAM's kernels specified segment would have rwx settable permissions > individually for different users and processes. > > Passwords should be related to master username, different ussers could have > different password for each service. > > Did already said that databasea can be passed in Kernell by passing > reference to write start, end and refill bucket function? Along > withmetadata of course. > > Filesystem operations(cp, mv, rm) could have main proccess that kewps track > of them, and lets you browse and rollback those. > > Option to make driver instance(the main os) just from hardware already > plugged in, not keeping unnecessary drivers in living memory, while > installing instances of os drivers doesn't play role. > > Always rewrite memory with pattern when allocating it to some process. > > Let the kernel be king of which sort algorythm to use and therefore we > should make sort an kernel operation, we pass metadata and data to kernel, > and also write head which writes or 3xecutes sorted data. > > Application for deconstructing XWindow or Wayland, also properly sorting > there. But any window should be blurable or even have different computed > layer on what's under that. > > Window snapping. With normalenviroments like plasma, we should also have i3 > like keyboard shortcuts to do operation on windows. > > Also we could hardly benefit from having guy, in which we can with keyboard > controll explore system. > > Live editor of memory on system, ability to stop a process in middle of > execution and examine it's memory {from master down we can examine even > whole kernels}. > > Graphic interface for users, groups. > > Graphic interface to explore recent network packets. > > Special filesystem, that store all text files in database with possible > undos and redos, and other files are stored normally on disk. > > Graphical program that let's us engrave simething into bits of HDD, like a > picture from it's magnetic potential. > > Snapshots of system lower instances, that can be stored on disk and played > later. > > Fingerprint authentification, > Face recognition that writes log about who sits on computer, like nobody > without password cannot replace you in computer chair and continue your > work. > > Optimize hashmaps in kernel. Like combination of checksum and skip table is > good. > > Brainstorm even weirdest optimizations over db you've ever heard. > > Compilers will have they own package system that'll automatically install > library for the compilation for header from public repository. > > If library haven't got it, it sort by kernel's sorting function, compiler > adds binary search when applicable, optimizes hashmaps based on benchmarked > performance in specific application. > > Graphic editor of bootloader menu, splash screen documentation, linux > command tip on loading showed on screen. > > File system for images, which use AI to categorize them and sort them. > > Best of all 'script' javascript derivative for event driven asynchronous > operation scripting. With all the system entries of services, possibility > to change config and reload it. Having ORM system for kernel database. > Having also good date and time functionality and full power to do API > calls. > > If you are registered at webservice, you can get your own url, which may > act as webhook for this API service. > > Kernel will also have some conditional loops, it's graph, along with whole > instance would be parsed trought looking for malicious behaviour. > > Script should be also capable to control web browser to some extent. > > Also gui to browse and change all the data provided to instance, including > strings, fonts, patterns, barelly anythint. > > Online repository for live wallpapers out of generative art. > > API SDK repository. Yea, script will have SDK's ready, that's why yoy > should develop open standards for information transfer and requesting. > Binnary with metadata about format is best way to go. Open API standards, > datatype standards and their version. > > Possible two factor authentification if computer is connected to internet > or with bluetooth. > > Possible authentification for wheel group by common access card along with > fingerprint and password. > > When reversing array itetation, just replace op code in instruction stack > with one that does reduce pointer and returns lenght-current as position. > > Analyze executed binaries by asynchronoys acyclic graphs with cyclic > groups, in GUI, to know they are going to do something that shouldn't be > there. They can be verified once saved checksum, and if no much change in > checksum, then don't commit whole analysis again. Some points are going to > be different, but it's whole picture that matters. > > Also, have I mentioned, you can have digital well beings apps down from > this everything is database thing, and with that data you can have like > automatic selection of music, that gets along with your current situation. > > Note-taking app, that support hypertext, keywords, autographing, and > 'script' and database, would be really useful too. > > And you could pick, which or what kind of data you will sync to your phone. > > And when it comes to your phone, it can have pre-fetched content for > offline browsing. > > And you can sync it with bluetooth/wifi/VPN so you can read reports from > computer on the way to work. > > Also audiofiles should be database, vectorized for simillarity search, > stored on specific file system, along with metadata, and if they are fresh > maybe they are still seedbacking to community trought peer to peer sharing. > Preffered format:FLAC with cache size of dictionary, prefferably big common > dictionary, and then separate derivatives of compresion core. > > Part of hard disk non encrypted bootable system, that boots only to ram and > have very restricted functionallity. > > Also for 16GB RAM swap with hibernate you need 32GB's of RAM. > > Filesystem with rollbacks possible. Even rollback with persist something is > programatically possible. > > Kernel wide memento for undo button that carries inverse of any function > done, or original of cow's before change on part and undoes even that you > copy pasted something. > > That's All Folks. >

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Re: Kernel Improvements
by Michael Sept. 26, 2023

Sept. 26, 2023

The philosophy "everything is a file" is a cornerstone of UNIX and Linux design, offering a unified interface for interacting with resources, be they hardware or software. Shifting to a paradigm where "everything is a database entry" or "active record" introduces a layer of abstraction that could compromise the simplicity and directness for which Linux is renowned. 1. **Performance Overhead**: Databases introduce latency and CPU overhead, affecting system responsiveness. 2. **Complexity**: Managing schemas, indices, and transactions adds unnecessary complexity for basic operations. 3. **Scalability**: File operations in Linux are optimized for performance and can scale horizontally. A database model may not offer the same scalability without significant engineering. 4. **Compatibility**: Existing applications rely on file-based APIs. A transition would necessitate widespread code changes, breaking backward compatibility. 5. **Principle of Least Astonishment**: Linux users expect a file-based paradigm. Changing this could alienate a significant portion of the community who rely on existing interfaces and behaviors. 6. **Transparency and Control**: Databases are often opaque, whereas the "everything is a file" design gives developers direct access to resources, offering more control. While innovation is vital, it's crucial to weigh these concerns carefully against the benefits your proposal might bring.

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Small MSS in vmxnet3
by Naruto Nguyen Sept. 25, 2023

Sept. 25, 2023

Hello everyone, Recently I found that packets sent from vmxnet3 driver on guest have MSS value set to very small size, some 10 bytes, some 25 bytes MSS. The vmxnet3 NIC enables TSO. Could you let me know any possible reason that the packets are fragmented with very small MSS.and is it normal?. Any way to avoid this small MSS or it's just normal. In addition, when enabling debug for vmxnet3, in function vmxnet3_tq_xmit, it has a printout netdev_dbg(adapter->netdev, "txd[%u]: SOP 0x%Lx 0x%x 0x%x\n", (u32)(ctx.sop_txd - tq->tx_ring.base), le64_to_cpu(gdesc->txd.addr), le32_to_cpu(gdesc->dword[2]), le32_to_cpu(gdesc->dword[3])); could you suggest an easier way to extract the MSS value from this output? Thanks, Kind regards, Naruto

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Re: [Question] dt bindings for BeagleConnect
by Ayush Singh Sept. 23, 2023

Sept. 23, 2023

> On 23/09/2023 18:08, Ayush Singh wrote: >> Hello everyone, I am working on writing a BeagleConnect driver for >> Beagleplay board. Let me first go over some terminology: >> > Sending things twice will only make discussion even more confusing for > us, e.g. spread over multiple threads. Don't do it. > Sorry, I sent the first using wrong email and then canceled the message from the link I got back from the mailing list.

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