Sections: Main page Security Kernel Distributions Development Commerce Linux in the news Announcements Back page All in one big page See also: last week's Back page page. |
Linux links of the weekAppwatch.com has just entered its "beta" stage. Appwatch is another database of free software; their angle is that they list only free software, and they keep a watch on their database and clean out entries for dead projects. Appwatch is built on Zope and PostgreSQL. Learn how the other side thinks. Here's an anti-Linux page that may be worth a look - successful advocacy depends on an ability to counter the opposition's arguments. See also the Sawman's Consortium, complete with its "Linux Lies" document. (Please do not flame the maintainers of these sites, that will not do any good for anybody). Section Editor: Jon Corbet |
September 23, 1999 |
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Letters to the editorLetters to the editor should be sent to letters@lwn.net. Preference will be given to letters which are short, to the point, and well written. If you want your email address "anti-spammed" in some way please be sure to let us know. We do not have a policy against anonymous letters, but we will be reluctant to include them. | |
Date: Wed, 15 Sep 1999 22:35:17 -0700 From: Raph Levien <raph@acm.org> To: editor@lwn.net, raph@acm.org Subject: Some clarifications on the tp600 Hi lwn'ers, Very nice writeup of the tp600 compatibility issue. As a tp600 Linux user and maintainer of a tp600 page (http://www.levien.com/tp600.html), I have been tracking the modem issue quite carefully, and have had some interesting conversations recently with people about what it means to be "compatible" with Linux. First, a small factual clarification. The modem in the tp600 may be considered a WinModem, but the processing is done by an on-board DSP chip (the MWave), not by the host processor. Further, your statement that the lack of interface specs is what's holding back WinModem compatiblity is also not true. All important specs on the MWave are in fact public (Linux driver writers have worked with a lot less). What's missing is the important software and/or firmware that makes a modem a _modem_, rather than just a pile of telephone interface circuitry, A/D and D/A converters, and digital logic. The free software community has not yet come up with such a piece of software. If it had, the WinModem issue would be moot. Incidentally, Russ Nelson's http://www.linmodems.org page is an interesting step in this direction. From what I can tell, it would be fairly easy for IBM to make the modem work under Linux. This is based on both familiarity with the technical issues and some informal conversations with IBM'ers. The software is already written and ships with Windows 9x. If IBM were unwilling to release it as free software, I don't think anyone would fault them for releasing it as binary-only. Indeed, one other vendor of WinModems already has: http://www.linuxworld.com/linuxworld/lw-1999-08/lw-08-linmodem.html So what I think galls me about this is that IBM is reaping the publicity goodies of being the first certified Linux Compatible laptop without having actually _done_ anything. For what surely must be less than the marketing expenses associated with the certification, they could have made the modem work. That said, "Linux compatibility" is a fuzzy concept (a friend pointed out to me that Linux itself is a fuzzy concept, when you get down to it). On any given computer, you'll find that some things work perfectly right out of the box, other things work pretty well with little hassle, still other things can be made to work if you have infinite patience (currently, IrDA and USB seem to fall into this category), and lastly you've got the things that just flat out don't work at all. Hopefully, all the really important stuff falls into the first two categories. But beyond that, where exactly do you draw the line on what's considered compatible and what's not. If the TP600 were sold with an epoxy plug over the RJ11, would it be more compatible? What about those servers with neat new features for diagnostics and failover that are not supported by Linux yet? As with most things in reality, it's complicated. A blanket certification of the TP600 as "Linux Compatible" conveys very little real information to me. If you really want to know how well a laptop runs Linux, the best resource by far is the Linux laptop page: http://www.cs.utexas.edu/users/kharker/linux-laptop/ Thanks again for a good article. Raph | ||
From: Nathan Myers <ncm@linuxlaptops.com> To: letters@lwn.net Subject: Winmodems and Thinkpads In the Sept. 16 edition of LWN, you wrote: [The IBM Thinkpad's built-in modem] is a "WinModem" - a modem that requires most of the signal processing to be done by the central processor. There is no reason why such modems shouldn't work under Linux, except one: the interface information for these modems has not been made available by their manufacturers. This information is all protected under non-disclosure agreements; thus, no Linux driver can be written. First, "WinModem" is a trademark of 3Com, Inc. A "winmodem", generically, is one that can only be used in Windows, either because the manufacturer won't release the specs, or because no self-respecting Linux hacker would bother to write code for it. However, not all non-traditional modems should be called "winmodems", and not all winmodems lack signal-processing oomph. The quoted paragraph conflates two very different devices. A dumb winmodem is little more than a mono sound card with a phone jack. It is the driver, in a sense, that _is_ the modem. Given a fast CPU and a real-time kernel, a sophisticated driver could, in principle, perform well; in effect, your whole computer would become a modem that can do other things too. In practice, Linux is not a real-time kernel (neither is Windows), and sophisticated drivers for these devices are, on any OS, rare -- perhaps nonexistent. A DSP winmodem has its own CPU, and is almost the same as a traditional modem, but lacks ROM. It depends on the driver to download its program to it, just as some very popular SCSI controllers need to be initialized with a program image provided by the vendor. (We don't call these "winSCSIs" because vendors do provide the program image.) Normally, as with ISDN modems, the driver fields the "AT" commands itself and talks to the DSP program at a lower level. The program needed to make a raw DSP device act as a reliable modem is easily as large and complicated as an IP stack, and as subject to improvements and bugs. IP Networking has a tradition of Free "reference code", yet it has taken many years and several rewrites to get Linux's network stack into a respectable state. I know of no reference V.90 implementations. Much of the value of 3Com's modem division is in its ownership of its modem code. While the PCTel modem that is common in laptops is a dumb winmodem, devices based on Lucent's product, like the Thinkpad's built-in modem, have true DSP capabilities, and lack only a driver to operate them. In fact, the specs for the Lucent device are already in developers' hands. Is the Lucent device really a winmodem? No driver is available, but the specs are not secret. No one has taken on the job of writing a driver yet. Probably none will exist until an enlightened company manages to Free up its private implementation, according to some yet-undiscovered business plan. (Still, see http://www.linmodem.org/.) IBM's Thinkpad presents a more complicated case: most of the devices in the machine, including parallel, serial, and sound, are operated by the same DSP coprocessor that "does" the modem. Programming it and interfacing with it are correspondingly messier -- indeed, most problems with Linux on Thinkpads involve the DSP device. (Curiously, the same problems manifest in Windows. IBM calls these bugs "Considerations".) IBM has shown some desire to get their modem supported on Linux, but (if I understand correctly) they seem to be having a hard time finding somebody for their lawyers to talk to. Generally, though, built-in modems are not such a big problem as is often suggested. Excellent PC-Card (PCMCIA) modems are available, and a good PC-Card modem may work far better than the built-in one ever can. A much bigger problem for laptop users is the continuing instability in sound, USB, and IrDA hardware, because those can't be bypassed the way a built-in modem can. Nathan Myers ncm@linuxlaptops.com http://www.linuxlaptops.com | ||
Date: Thu, 16 Sep 1999 11:36:34 +0200 From: Rodolphe Ortalo <Rodolphe.Ortalo@cert.fr> To: lwn@lwn.net Subject: A comment on DRM (LWN, Sep. 16) Hello, in Sep 16 issue of the LWN, under the 'Kernel development' section, concerning the new Direct Renderimg Manager, you say that: "... The result should be secure access to low-level hardware and screamingly fast 3D graphics. More information on DRM can be found on the DRM design document;..." In fact this is a little inaccurate. The DRI should provide something that is (only) as secure as the X server. (Even the DRM design document acknowledges this, as I understood it.) Unfortunately, X11 servers security is still extremely poor. (I hope I do not need to explain this statement... Ask if you want but I'd rather keep that email short.:-) Non-withstanding security issues, safety issues are no more adressed. The DRM does not provide any arbitration or access control with respect to broken hardware etc. For example, some good old S3 cards simply lock the PCI bus when a MMIO access is done while the graphic accelerator is running. This is a hardware bug of course. But the DRM does not protect the machine against this. Neither does the X server (which only mean of control would be to deny to applications the access to DRM-related features - thus denying DRM interest on these cards). Graphic hardware dependability is currently improving, but it has a long way to go... Well, anyway, I simply think that security or safety is not among the design objectives of a thing like the DRI. (If it were they would not simply assert the fact that the X server needs root privileges as a security features...:-) The objective was/is "screamingly fast 3D graphics". IMHO, this is a perfectly respectable objective. :-) But suggesting that this kind of architecture can bring also security or safety improvement is, in my opinion, a giving a false impression. Anyway, that's just a personal comments... Regards, Rodolphe Ortalo | ||
From: "Michael Callahan" <michael@ask.com> To: <lwn@lwn.net> Subject: direct rendering explanation in 9/16 LWN Date: Wed, 22 Sep 1999 15:44:10 -0700 Hi, Thanks again for the wonderful Linux Weekly News! In last week's issue, in the Kernel Development section, the following explanation appears: >The Direct Rendering Manager (DRM) has also been put into the kernel. >DRM is the kernel-level support needed for the Direct Rendering >Infrastructure (DRI), which will be part of XFree86 4.0. Essentially, >DRI pushes the handling of three-dimensional rendering into the X >server. The server, in turn, can take advantage of the rendering >capabilities provided by the video hardware. The result should be >secure access to low-level hardware and screamingly fast 3D graphics. In fact, direct rendering is basically the opposite of what is described here. When the X server does 3d rendering, that's called indirect rendering--because the 3d data passes from the application, through the X server, and into the 3d video card. Direct rendering allows applications themselves to send their data directly to the video card. For 3d graphics, where there can be very high volume streams of data, this can be vital. Michael | ||
Date: Fri, 17 Sep 1999 08:31:26 +0200 (CEST) From: chimbis@skjoldebrand.org Subject: A couple thing off my chest To: letters@lwn.net Just got to get a couple of things off my chest, so to speak. 1/ Standards. Linux badly needs standards. Not perhaps strictly to satisfy a real need within the community but to better it's reputation. I recently saw (I think it was) an add for Veritas Backup Exec for Linux, which is available for Red Hat, SuSE, and Open Linux with a version for TurboLinux soon to follow. Another product was available for Red Hat with other distros to follow soon. This is ridiculous, considering that there isn't really a compatibility issue to talk about. People are just stuffing files in different places which in fact is making it hard for companies in porting software that will work across all Linuxes. This is stupid. 2/ One wonders what impact on Linux badly tested, originally Windows software is going to have on our favourite OS. I have in mind a piece of ported software that is quite buggy and even crashes at irregular instances. It is however, quite feature rich so many people would probably like to try to use it. These software packages could damage Linuxes reputation for quality. Just a thought. Cheers, Martin S. -- Martin Skjöldebrand, Chimbis Design Sys admin, web design Hungry? Visit The Olde Cookery Book at http://www.bahnhof.se/~chimbis/tocb/ | ||
Date: Wed, 22 Sep 1999 12:42:37 +0530 From: ANAND <anand@nmi.stpn.soft.net> To: dvorak@zdnet.com CC: letters@lwn.net Subject: The Linux Myth Hi, I find your contention, that Linux will not make it in the server arena because it is not very stable, laughable. How is it that NT that can't stand on it feets for more than a week is still considered as a strong contender in the server arena if stability and reliability were that important. Linux is obviously much better in these respects. Linux may not be the most stable OS, but there are some other things that make it ideal for the server arena, lack of licensing restrictions. Its also probably the most efficient of all OSs. The only two places were linux lacks is in scalability, and User Interfaces, but there too not by much. Low scalability will prevent it from entering the arena of the super large systems, which cannot be handled by a single Quad Processor system. But then NT also lacks those things. UI problems are more of a perception problem, and as you say won't matter for the ultra cheap systems. I would like to point you to the latest SAP R/3 benchmarks for Linux, which claimed that they were the best reported for any Quad Processor systems. That would definitely include NT. Anyway the biggest thing that you forgot was that Linux has the biggest developers resource. No Company can compete on that ground, and anything proprietory, will become less and less competitive will Linux as time progresses, because as internet expands, Linux's talent pool will keep on increasing. -anand | ||
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