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diff --git a/open_issues/benefits_of_a_native_hurd_implementation.mdwn b/open_issues/benefits_of_a_native_hurd_implementation.mdwn new file mode 100644 index 00000000..dfd41837 --- /dev/null +++ b/open_issues/benefits_of_a_native_hurd_implementation.mdwn @@ -0,0 +1,139 @@ +[[!meta copyright="Copyright © 2010, 2011, 2013 Free Software Foundation, +Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag open_issue_documentation]] + +What are the benefits of a native GNU/Hurd system, now that Linux et al. can do +so much? Think [[hurd/translator]]s: FUSE, [[hurd/subhurd]]s: User-Mode-Linux +and other virtualization techiques, and so on. + +It is possible to begin [[implementing_Hurd_on_top_of_another_system]], but... + +IRC, #hurd, August / September 2010 + + <marcusb> ArneBab: but Neal and I were not happy with that alone. We were + looking for deeper improvements to the system, for, I think, sound + reasons. That is what brought us to the L4/Coyotos technologies + <marcusb> ArneBab: as you are writing a kernel in user space, you can still + do kernel improvements there + <marcusb> ArneBab: if you take it very far, you end up with a kernel that + runs Linux in user space (just flip the two) for the drivers + <marcusb> ArneBab: that is what the L4 people did with the DDE + +[[/DDE]]. + + <marcusb> ArneBab: so, with these different cuts, there are different + opportunities. on the one end, you can run Linux as normal and get some + of the Hurd features such as translators in some programs. At the other + end, you can do whatever you want and run some linux code for the drivers + or none at all. + <marcusb> ArneBab: one of the big questions then becomes: at which point + can the advantages offered by the Hurd be realized? + <marcusb> ArneBab: and that's not entirely clear to me + <marcusb> when I worked on this with Neal, we pushed further and further + into need-to-change-everything land + <marcusb> while the current efforts on the Hurd seem to be more equivalent + to the could-run-it-in-userspace-on-top-of-Linux camp + <ArneBab> marcusb: for that I think we need a way to move towards them step + by step. Would it be possible to get the advantages of better resource + allocation with a Viengoos in userspace, too? + <ArneBab> and when that is stable, just switch over? + <marcusb> ArneBab: I don't know. I suspect these people will know before + us: http://lxc.sourceforge.net/ + <ArneBab> something like implementing flip points: flip Linux with Hurd to + Hund with Linux. Flip Mach with L4 to L4 with Mach. + <ArneBab> lxc sounds interesting. + <marcusb> note that these efforts address security concerns more than other + concerns + <marcusb> so they will get isolation long before sharing is even considered + <marcusb> but some of the issues are the same + <marcusb> once you allow malware to do what it wants, it's a small step to + also allow the user to what he wants :) + <ArneBab> it kinda looks like hacking it where it doesn’t really fit again… + <ArneBab> there I ask myself when the point comes that doing a cleaner + design offsets the popularity + <ArneBab> they are pushing more and more stuff into userspace + <ArneBab> which is a good thing (to me) + <ArneBab> it’s hard to clearly describe how, but even though I like having + more stuff in userspace, the way it is bolted onto Linux doesn’t feel + good for me. + <ArneBab> FUSE is cool, but if I use it, I am at a disadvantage compared to + a non-fuse user + <ArneBab> while in the Hurd, these additional options are on eqal footing. + <marcusb> ArneBab: are they pushing more and more into user space? I don't + think so. I see more of the reverse, actually + <marcusb> or maybe both + <ArneBab> FUSE, lxd and scheduling in userspace move to userspace + <ArneBab> well, KMS moved to the kernel + <ArneBab> to avoid flickering when switching between X and the console? + <ArneBab> marcusb: Do you experience FUSE lxc and such being secondclass in + Linux, too, or is that just a strange feeling of me? + <ArneBab> marcusb: and that splits the users into those who can get stuff + into the kernel and those who can only work in userspace – which I don’t + really like. + <ArneBab> That’s one more advantage of the Hurd: eqal footing for all + (except the Mach hackers, but they have a very limited terrain) + <marcusb> ArneBab: but UML kernel module is minimal, and Linus didn't have + a principled objection to it (but just wanted a more general solution) + <marcusb> ArneBab: as a side note, although people keep complaining, the + linux kernel seems to be growing steadily, so getting stuff into the + kernel doesn't seem too hard. 8-O + +--- + +IRC, #hurd, 2010-12-28 + + <tim> but is monolithic so bad? + <sartakov> yep + <braunr> no it's not + <braunr> proof: it works very well for most people + [...] + <braunr> the real problem is extensibility and interfaces + <tim> :/ whats the huge advantage of micro-k + <braunr> extensibility + <tim> over? + <braunr> you can add a whole lot of new services for new purposes with new + interfaces without changing the kernel + <tim> oright + <braunr> it basically boils down to the original Unix idea: everything does + one thing well + [...] + <kilobug> well, I would say extensibility and fault-tolerance are the two + key advantages + <braunr> taht's a side effect + <braunr> there are fault taulerant monolithic kernels + [...] + <braunr> tolerant* + <braunr> and the hurd is for now a non fault-tolerant microkernel based OS + :/ + [...] + <kilobug> braunr: not really; you can't ensure fault tolerance for code + running in kernel space, code running in kernel space can do everything, + including reboot, crash, ... + [...] + <braunr> kilobug: right, a monolithick kernel is less folt-tolerant than a + well designed/implemented microkernel based os + +It turns out that it is perfectly possible to isolate services running in the +same address space, as it was done in projects such as Singularity, the idea +being that the code is verified through static analysis when installed (but +this requires a language other than C). + + <kilobug> braunr: well, the Hurd is buggy nowadays, but things like an + ext2fs translator doing a segfault and being restarted is a + fault-tolerance that would be almost impossible to have in Linux + <kilobug> braunr: sure, you can have fault-tolerance with FUSE, but FUSE is + applying micro-kernel paradigm to Linux + [...] + <braunr> the reason i don't care that much about fault tolerance is that + Linux obviously shows a monolithic kernel can run almost flawlessly if + well written + <braunr> but extensibility is really another matter |