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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [RFC PATCH] xen/design: Add design for EFI dom0less system start
> On 7 Sep 2021, at 10:24, Jan Beulich <jbeulich@xxxxxxxx> wrote: > > On 07.09.2021 11:17, Julien Grall wrote: >> On 07/09/2021 09:33, Jan Beulich wrote: >>> I'd like to suggest a different scheme, not the least because I expect >>> the individual domains being independent of e.g. hypervisor command >>> line options or Dom0 kernel versions. Yet varying sets of these are, >>> for example, a reason to have multiple sections in the current scheme. >>> Every dom0less guest would then require spelling out in every such >>> section. Hence I think we'd be better off having a section per guest: >>> >>> [guest1] >>> kernel=Image-domu1.bin console=ttyAMA0 root=/dev/ram0 rw >>> property=cpus=1 >>> property=memory=0xC0000 >>> dtb=domu.dtb >> >> I much prefer the idea of the section. This is going to be easier to >> parse the configuration file as we would not have to look for "domuX_" >> and then distinguishing X. >> >>> >>> These sections would then be referenced by other sections, e.g. by a >>> new "guests" (or "domus", but this ends up looking a little odd for >>> its matching of an unrelated latin word) keyword: >>> >>> guests=guest1,guest2 >>> >>> If it is deemed necessary to make sure such a section can't be >>> (mistakenly) used to create Dom0, such sections would need identifying >>> in some way. Presence of property= (or, as per below, properties=) >>> could be one means (allowing an empty setting would then be desirable). >> >> I would expect dom0 to be described in the similar fashion at some >> point. So maybe we should name the property "domains=...". > > Not sure - the order above doesn't mandate domain IDs, yet Dom0 needs > creating with ID 0. IOW I was deliberately suggesting "guests=". Hi Jan, Julien, Thanks for your feedbacks, really appreciated, I agree with you that sections are easier to read. I stand with the “guests=“ or “domus=“ or “domu_guests=“ keywords where the references to “guest sections” can be listed, separated by commas. > >>> As to the properties, is there anything wrong with having them all on >>> one line: >>> >>> [guest1] >>> kernel=Image-domu1.bin console=ttyAMA0 root=/dev/ram0 rw >>> dtb=domu.dtb >>> properties=cpus=1 memory=0xC0000 >> >> It depends on the number of properties for the domain, this may become >> quickly unreadable. >> >> But... if we use sections, then I think it would be better to have: >> >> kernel=.. >> dtb=... >> cpu=1 >> memory=0xC0000 >> >> This would also allow us to create more complex setup (such as for the >> static memory allocation). > > If that's feasible parsing-wise - sure. I was first thinking to suggest > separate keywords, but then decided there was a reason this wasn't done > in the original proposal (with respective dom#_ prefixes). Yes I think it is feasible and easy to read, so given your feedback we can agree on something like that: [global] default=xen [xen] options=[xen command line] kernel=[dom0 kernel file] [domain 0 command line options] ramdisk=[dom0 ramdisk] xsm=[xsm filename] dtb=[xen device tree blob] domu_guests=guest1,... [guest1] address-cells=2 size-cells=2 kernel=[domU kernel file] [domU command line options] cpus=1 memory=0xC0000 dtb=[domU passthrough dtb] This won’t break the compatibility because on older version the domu_guests keyword Is ignored, the user needs just to check that a guest section is not specified as default= argument because in this case it will be loaded as dom0 kernel (and probably won’t work), but I think we can just update the documentation to highlight this thing. Finally this example should load a dom0less system: [global] default=xen [xen] # Xen boot arguments options=noreboot console=dtuart dtuart=serial0 bootscrub=0 # Xen device tree dtb=devtree.dtb # domus to be started domu_guests=guest1,guest2 [guest1] address-cells=2 size-cells=2 kernel=Image-domu1.bin console=ttyAMA0 root=/dev/ram0 rw cpus=1 memory=0xC0000 dtb=domu.dtb [guest2] kernel=Image-domu2.bin console=ttyAMA0 root=/dev/ram0 rw cpus=2 memory=0x100000 vpl011 > > Jan >
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