On Sat, Aug 1, 2020 at 2:46 PM <evan.mesterh...@gmail.com> wrote: > > You're right - after re-reading this I realize I could have been more > specific. > > I am working with a custom OS kernel that supports a subset of Linux > syscalls. However, it does not support TLS, which on i386 I believe typically > requires OS support to set up and restore the GDT and %gs segment register > between context switches. > > My understanding is that TLS using segment registers on i386 is largely a > speed and syntax optimization, but that thread specific data can be managed > without it (see glibc's pthread_setspecific() api). I am currently building C > programs for this OS by compiling for Linux / i386 using uClibc-ng configured > to disable TLS. I'm wondering if there is a similar configuration option to > build Go programs without TLS so that I can run them on my OS. > > Please let me know if I can clarify anything further.
While technically it might be possible to use something like pthread_setspecific to handle Go's needs, 1) there is no support for that in the current toolchain; 2) the execution time cost would be significant. On x86 Go currently stores the stack guard in an offset from the TLS segment register, and it checks that value at the entry to (almost) every function. Requiring some sort of function call would be a big slowdown at every function call. Also, come to think of it, I'm not sure how to implement it; even pthread_setspecific relies on TLS. One option would be to change Go on x86 to store the required information in a register. That is how it works on some other processors, so it would be feasible, but not at all simple. And you would be using a custom port of Go that would not interoperate with standard Go. Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcWGsn0_4QV1Cp7LWDzb7eGj9n1LjR8qWxeBPjK%3DED7ttA%40mail.gmail.com.
