On Sat, May 24, 2014 at 01:39:44PM +1000, Peter Jeremy wrote:
> On 2014-May-24 02:34:44 +0300, Konstantin Belousov <kostik...@gmail.com>
> wrote:
> >On Fri, May 23, 2014 at 04:28:34PM -0700, Peter Wemm wrote:
> >> On 5/23/14, 4:22 PM, Peter Wemm wrote:
> >> > On 5/23/14, 3:53 PM, Peter Jeremy wrote:
> >> >> I've been playing with Go (lang/go) and found that i386 Go binaries
> >> >> segfault when run on amd64 (9.x, 10.x or HEAD). I've narrowed it down
> >> >> to the LDT handling but am not sure whether it's on the FreeBSD or Go
> >> >> side.
> >> >>
> >> >> As far as I can see, the i386 binary is correctly calling i386_set_ldt()
> >> >> and the i386_set_ldt() emulation in the amd64 kernel matches the i386
> >> >> kernel - but the net result doesn't work.
> >> >>
> >> >> Can anyone offer any suggestions as to how to resolve this?
> >Provide the minimal test case.
>
> The following go program, compiled on i386 and run on amd64 will die
> with a segmentation violation or bus error:
> -------
> package main
>
> import "fmt"
>
> func main() {
> fmt.Println("Hello World")
> }
> -------
No, this is not consumable.I need a self-contained minimal example written in C/asm. If this is too hard to produce, give the the self-contained binary, again as small as possible (small by comparing the number of syscalls before the issue manifests itself). As the absolute minimum I could start with the output on ctty with machdep.uprintf_signal=1, but it is only for beginning. > > >> >> > >> > We don't emulate i386_set_ldt(). > >> > > >> > The 32 bit version of libc on amd64 has a different implementation > >> > that calls sysarch(I386_SET_FSBASE, ..) and friends. Normally this is > >> > handled transparently by static linking, but obviously that's an issue > >> > for Go. > >> > >> Actually, that's an even more interesting question. WHY are they using > >> i386_set_ldt()? Where is it coming from? As near as I can tell, libc, > >> libthr etc call I386_SET_GSBASE for tls. > > As installed, the code is in /usr/local/go/src/pkg/runtime/sys_freebsd_386.s > "runtime·setldt", which calls "runtime·i386_set_ldt" which uses "int 128". > > >We do support ldt for 32bit binaries on amd64. > > I thought it was supported. > > -- > Peter Jeremy
pgpulElM5Nr6C.pgp
Description: PGP signature
