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9vJ3bcfUBreJRjpcxwhWBIb-c7J3Jla2 Hi Fangrui. > - https://maskray.me/blog/2025-09-28-remarks-on-sframe (covering > mandatory index building problems, section group compliance and > garbage collection issues, and version compatibility challenges) After reading your blog it seems to me that your main concern is (was?) that SFrame "violates ELF rules" because it is not amenable to concatenation (the result of concatenating two "sframes" is not a valid sframe) and thus it requires specific linker support to merge these sections. This support, once in place, will have to be maintained moving forward, and evolved along with the format. First, SFrame is not concatenable because its main design goal is to be simple to _use_ (not necessarily trivial to link) so it provides little luxuries like a fixed-size header (uoh), it is self-contained, it does not require an explicit index to be searched efficiently (instead you just binary search on the data in place), it has no run-time relocations, etc. You don't need to allocate memory dynamically to decode and stack-walking using SFrame, and it has even been proved (by the parca project people) that it is possible to write actual verifiable BPF to walk an userspace stack using an internal format that is in essence identical to SFrame. You may not care about any of that, but the people wanting to use the format certainly do, and thats the reason SFrame (and ORC for that matter) is the way it is. Sure, nobody would object making SFrame concatenable to make your (and mine, incidentaly) life easier, but not at the cost of burdening users with extra complexity that they dont need and are not willing to assume: why would they? We are not even quite sure if such a thing is achievable in this case: you either put the complexity in the linker, or on the users, but you cannot make it magically disappear. If you have some _concrete_ suggestion on improving the format, please by all means let the SFrame people know, or consider following-up in threads like [1] where these details are being discussed. That would be helpful indeed. Second, as bizarre as it may be, having non-concatenable data in an ELF section only "violates ELF rules" if the linker _doesn't know_ about the type of the section containing it. So the solution is obvious: make your linker aware of SFrame sections and, voil=C3=A0, the ELF violation goe= s away. You can either merge the SFrame data, or just discard the input sections, or call the Linker Police. Just do _something_ about it, because doing nothing leads to emitting nonsense, and that pisses off everyone. Third, this "problem" is not privative to SFrame. Other formats like EH Frame also require some degree of linker awareness, in the form of the generation of an explicit index, or merging, or whatever... apparenlty to nobody's scandal, lucky them. Pushing the burden of dealing with this to users or to post-processing tools, like you suggest in your blog, is IMO hardly a satisfactory solution: it is rather a no-solution and an attempt of making your problem everyone's problem. Now, if you then move the goalpost and claim the problem is the _degree_ of linker involvement, as you seem to suggest in your blog, then again your feedback is very welcome to make SFrame more linker-friendly, as long as it is in the form of concrete construtive suggestions _and_ not at the cost of the user's requirements for the format. Fourth, some people think that it is unreasonable to expect all the ELF linkers in existence to be aware of SFrame sections (not me; you can count them all linkers with fingers and no toes). ELF already supports a standard section flag SHF_OS_NONCONFORMAT that tries to deal with cases like this... and fails miserably: unknown sections marked with that flag are not required to be amenable to concatenation, but the problem is that upon encountering them the linker is expected to abort the link with an error. This is hardly convenient for anyone, so the SFrame people are currently proposing to the gABI [2] the addition of a new flag SHF_OS_NONCONFORMANT_DISCARD that would make the linker to just discard the unknown input section rather than aborting the link. Fifth, the problems related to GC and section grouping were discussed during Cauldron [3] and I believe a solution has been already found, proposed independently by Roland in the gabi discussion thread. I think that solution is being written down and will have to be reviewed before being used in SFrame V3. Your help on that review would be also very much appreciated, considering your vast experience on these matters. I suppose it will happen in the binutils list. I am sure they will CC you in the relevant thread so you won't miss it. Sixth, several people have repeatedly pointed out that it is not reasonable to extrapolate the big gap between SFrame V2 and V3 to future revisions of the format, and that not implementing V2 in lld is perfectly ok, because the kernel will start directly with V3. The SFrame maintainer has assured, also repeteadly, that she is well aware that any change in the spec will have to be very carefully considered to avoid or minimize any impact in the linkers. I would say the fact she also maintains the SFrame support in ld may also serve as bail to guarantee her good behavior, at least to some extent ;) Finally, it is not clear to me at all why supporting SFrame would result in such an unbearable burden to lld's maintenance, as you seem to expect, given everyhing is fine on the GNU side. Please don't misunderstand me: you know your linker better than anyone else and I am sure there are good reasons that justify such apprehension. What is it? Is it lack of contributors? Is the lld codebase particularly difficult to maintain or extend? Looking at [4] the people that are contributing the SFrame support to LLVM are also volunteering to maintain it moving forward.. isn't that enough? Perhaps you need a co-maintainer? Can we, or anyone else, help somehow? If so, how? Salud! [1] https://sourceware.org/pipermail/binutils/2025-October/145086.html [2] https://groups.google.com/g/generic-abi/c/3ZMVJDF79g8 [3] https://www.youtube.com/watch?v=3DL2UmAp39xqk [4] https://discourse.llvm.org/t/rfc-adding-sframe-support-to-llvm/86900