On Mon, 2018-01-01 at 12:36 +0200, Konstantin Belousov wrote: > On Mon, Jan 01, 2018 at 06:52:37AM +0000, David Chisnall wrote: > > > > On 1 Jan 2018, at 05:09, Adrian Chadd <adrian.chadd_at_gmail.com> wrote: > > > > > > > > > On 30 December 2017 at 00:28, Konstantin Belousov wrote: > > > > > > > > On Sat, Dec 30, 2017 at 07:50:19AM +0000, blubee blubeeme wrote: > > > > > > > > > > Is there some way to programmatically get the CPU cache line sizes on > > > > > FreeBSD? > > > > There are, all of them are MD. > > > > > > > > On x86, the CPUID instruction leaf 0x1 returns the information in > > > > %ebx register. > > > Hm, weird. Why don't we extend sysctl to include this info? > For the same reason we do not provide a sysctl to add two integers. > > > > > > > It would be nice to expose this kind of information via VDSO or similar. There are a lot of similar bits of info that people want to use for ifunc and, SVE is going to have a bunch of similar requirements. > > > Is VDSO a new trendy word ? > > ifunc resolvers in usermode on FreeBSD/x86 get four arguments which > are essentially cpu_features / cpu_features2 / cpu_stdext_features / > cpu_stdext_features2. I suspect that only FreeBSD/x86 arches have the > ifunc support, in rtld and coming shortly in kernel. > > Recently HW_CAP/HW_CAP2 were added to the ELF auxv, and elf_aux_info(3) > interface exported from libc. > > ARM* did not implemented yet the ifunc stubs in rtld. I believe this is > considered a low priority because there is no ready to use toolchain > which allow to utilize ifuncs on FreeBSD, except if you use recent bfd > ld externally. Linux exports this info using getauxval(). I think we should support getauxval() and as many of the AT_* values that linux defines as makes sense for us to do. I think it was a mistake to give our version of the function a different name and different semantics, but this is something that affects mainly ports, and I don't yet have enough info to make the case that being linux-compatible will ease porting rather than complicate it (in some cases, patches will be needed either way). -- IanReceived on Mon Jan 01 2018 - 15:26:45 UTC
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