On Sun, Oct 16, 2016 at 02:14:47PM +0000, lumin wrote: > My package lua-torch-torch7/experimental fails[2] to build from > source because of an "illegal instruction" error at the debhelper > auto test stage. However from that buildlog I can't tell which > program to blame -- luajit or lua-torch-torch7. > > The upstream code indeed contains instruction specific stuff but > I have never encountered such failure on amd64 architecture. > Besides, I tested this package with debomatic-amd64[3] and the > result is quite healthy. > > So I have trouble allocating where the source of problem is. > > Cosmic ray? > > My questions: > > * should we suspect the health state of that amd64 buildd > machine «binet»?
I'd bet first on a real SIGILL. This can come from two sources: * using an instruction specific to a particular CPU, such as, say, ADDSUBPD on x86 with no SSE3, DMB on RasPi 1, MTVSRD on ppc64el when ran on qemu from jessie, etc * executing some junk memory Failing on the buildd but not on your home box suggests the former. If you don't have access to a diverse set of CPUs to test, I'd recommend using qemu _without_ kvm. You can choose a specific CPU to emulate via either QEMU_CPU=z80 or -cpu z80; "qemu-system-x86_64 -cpu help" to get the list of valid targets. Perversely, it's easier to test this from a non-x86 host as qemu-user+binfmt make running foreign binaries convenient -- if all what you have is a x86 box, I'd recommend qemu-system-x86_64 as using qemu-user for same ISA, while possible, is too tricky to get it right. qemu-system means you need to set up a whole virtual machine. > * what should I do next? do a binary-only amd64 upload or > request (and how) for a rebuild against that package? Please don't. It fails in the test suite, which means it'd break the same way on user systems that don't support that particular extension. > I encountered an unexpected FTBFS on amd64 that I can't repro.[1] > And I'd like to ask the list before fixing it by e.g. an binary > only upload. As the page at [1] is almost entirely red, I'd say you have a good deal more to investigate befor applying workarounds. Meow! > [1] > https://buildd.debian.org/status/package.php?p=lua-torch-torch7&suite=experimental > [2] > https://buildd.debian.org/status/fetch.php?pkg=lua-torch-torch7&arch=amd64&ver=0%7E20161013-g4f7843e-1&stamp=1476616893 > [3] > http://debomatic-amd64.debian.net/distribution#experimental/lua-torch-torch7/0~20161013-g4f7843e-1/buildlog -- A MAP07 (Dead Simple) raspberry tincture recipe: 0.5l 95% alcohol, 1kg raspberries, 0.4kg sugar; put into a big jar for 1 month. Filter out and throw away the fruits (can dump them into a cake, etc), let the drink age at least 3-6 months.
