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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Enhancing Xen's Kconfig infrastructure to support tailored solutions
On Thu, Feb 14, 2019 at 09:03:24PM +0000, Lars Kurth wrote: > > > > On 14 Feb 2019, at 18:32, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote: > > > > On Thu, 14 Feb 2019, Jan Beulich wrote: > >>>>> On 13.02.19 at 20:11, <sstabellini@xxxxxxxxxx> wrote: > >>> On Wed, 13 Feb 2019, Wei Liu wrote: > >>>> On Tue, Feb 12, 2019 at 09:34:25PM -0500, Daniel P. Smith wrote: > >>>>> Greetings, > >>>>> > >>>>> On the 11/14/18 Xen x86 community call a discussion was initiated about > >>>>> using Kconfig to build minimized versions of Xen for security, safety > >>>>> and other certification requirements. After some offline discussions > >>>>> with Xen contributors I realized that a variety of efforts each with > >>>>> their own respective goals are underway, > >>>>> > >>>>> - nested virtualization > >>>>> - mixed criticality architectures > >>>>> - reducing trusted componentary > >>>>> - combining hardware protection of virtualization with performance and > >>>>> ease-of-use of containers > >>>>> > >>>>> These efforts use hypervisors in different roles, all which Xen is > >>>>> capable of meeting. Today Xen's utility comes at the expense of carrying > >>>>> features necessary for one role to be present in another role where it > >>>>> is not required, e.g. PV interfaces that may not be essential in an ARM > >>>>> mixed criticality deployment. > >>>>> > >>>>> The initial focus will be to explore and document the range of possible > >>>>> use cases that are of interest to the Xen community. This will be the > >>>>> input to a design document that is crafted in conjunction with the Xen > >>>>> maintainers, to identify possible approaches to extend the existing > >>>>> Kconfig infrastructure to produce tailored instances of Xen. > >>>>> > >>>>> If you are interested in participating in this effort, please reply to > >>>>> this thread to outline possible use cases, design constraints and other > >>>>> considerations for improving Xen's Kconfig infrastructure to support > >>>>> tailoring for specific use cases. > >>>>> > >>>> > >>>> My impression from the community call is that you want to provide > >>>> smallish configurations for different use cases. > >>>> > >>>> The Kconfig infrastructure is already able to do what you want as far as > >>>> I can tell. You can easily feed it a base config file -- see files > >>>> under automation/configs/x86/. What sort of extension is needed in your > >>>> opinion? > >>>> > >>>> As use case goes, it would be a good start if you just submit something > >>>> you care about. > >>> > >>> I mentioned on the call that a good first start could be a kconfig that > >>> allows to build an hypervisor binary with only support for PVH and only > >>> support for recent Intel machines, with the goal of minimizing the code > >>> base to less than 100K LOC. > >> > >> "With only support for PVH" (which really means HVM) we already have. > >> "With only support for recent Intel machines" would require adding new > >> Kconfig options first, to control Intel, AMD, etc separately, and to then > >> further somehow separate "old" from "new" (which may turn out not > >> very easy to do without a lot of #ifdef-ary or other code churn). I'm > >> not aware of something like this existing on Linux either - all I'm aware > >> of there is a means to control what -m<arch> option might be passed > >> to the compiler, but without disabling any source code from getting > >> compiled. > > > > I was thinking along the lines of having options to disable drivers for > > older timers and older interrupt controllers that are not needed on > > recent machines. > > > > > >> And then "with only support for recent Intel machines" could also imply > >> HAP-only; disabling shadow code (which also is already possible) will > >> alone save almost 10k LOC (counting .c files only). > > > > I have just run `make cloc' on x86 with the smallest possible > > configuration (HVM only): > > > > > > http://cloc.sourceforge.net <http://cloc.sourceforge.net/> v 1.60 T=0.87 s > > (370.3 files/s, 255808.4 lines/s) > > ------------------------------------------------------------------------------- > > Language files blank comment > > code > > ------------------------------------------------------------------------------- > > C 309 33238 29432 > > 157001 > > Assembly 14 466 531 > > 2435 > > ------------------------------------------------------------------------------- > > SUM: 323 33704 29963 > > 159436 > > ------------------------------------------------------------------------------- > > > > This is great! The last time I did the count it was above 220K LOC. We > > should make more noise about this -- it is a major. > > @Wei: the binary size data is not that impressive. Would it be possible to do > the make cloc on HVM, PV and mixed? > I can include this into the PR for 4.12. Sorry for slightly hi-jacking the > thread. Not sure how Stefano got the 157k number. Here are some results from staging. * Full build cloc --list-file=/tmp/tmp.sSYTTwC8vo 368 text files. 359 unique files. 6 files ignored. github.com/AlDanial/cloc v 1.70 T=0.73 s (489.4 files/s, 342664.7 lines/s) ------------------------------------------------------------------------------- Language files blank comment code ------------------------------------------------------------------------------- C 336 35990 32543 174886 Assembly 19 700 918 3534 ------------------------------------------------------------------------------- SUM: 355 36690 33461 178420 ------------------------------------------------------------------------------- rm /tmp/tmp.sSYTTwC8vo * HVM only with shadow cloc --list-file=/tmp/tmp.dr9H29oAjZ 350 text files. 341 unique files. 6 files ignored. github.com/AlDanial/cloc v 1.70 T=0.70 s (481.2 files/s, 345675.6 lines/s) ------------------------------------------------------------------------------- Language files blank comment code ------------------------------------------------------------------------------- C 319 35114 31729 170552 Assembly 18 665 857 3188 ------------------------------------------------------------------------------- SUM: 337 35779 32586 173740 ------------------------------------------------------------------------------- rm /tmp/tmp.dr9H29oAjZ * PV only with shadow cloc --list-file=/tmp/tmp.iFlA6cYriw 307 text files. 300 unique files. 5 files ignored. github.com/AlDanial/cloc v 1.70 T=0.59 s (502.7 files/s, 338427.3 lines/s) ------------------------------------------------------------------------------- Language files blank comment code ------------------------------------------------------------------------------- C 280 28300 26343 140419 Assembly 17 658 848 3386 ------------------------------------------------------------------------------- SUM: 297 28958 27191 143805 ------------------------------------------------------------------------------- rm /tmp/tmp.iFlA6cYriw * HVM only without shadow cloc --list-file=/tmp/tmp.xX9DEaEw14 346 text files. 339 unique files. 5 files ignored. github.com/AlDanial/cloc v 1.70 T=0.69 s (487.1 files/s, 344973.4 lines/s) ------------------------------------------------------------------------------- Language files blank comment code ------------------------------------------------------------------------------- C 318 34576 30963 167736 Assembly 18 665 857 3188 ------------------------------------------------------------------------------- SUM: 336 35241 31820 170924 ------------------------------------------------------------------------------- rm /tmp/tmp.xX9DEaEw14 * PV only without shadow cloc --list-file=/tmp/tmp.w2YYkxG90d 302 text files. 299 unique files. 3 files ignored. github.com/AlDanial/cloc v 1.70 T=0.62 s (484.2 files/s, 319189.4 lines/s) ------------------------------------------------------------------------------- Language files blank comment code ------------------------------------------------------------------------------- C 280 27835 25697 137998 Assembly 18 660 848 3395 ------------------------------------------------------------------------------- SUM: 298 28495 26545 141393 ------------------------------------------------------------------------------- rm /tmp/tmp.w2YYkxG90d _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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