On Fri, Dec 14, 2018 at 06:13:33PM +0000, Szabolcs Nagy wrote: > On 11/12/2018 19:26, Dave Martin wrote: > > This patch refactors the UAPI header definitions for the Arm SVE > > extension to avoid multiple-definition problems when userspace mixes its > > own sigcontext.h definitions with the kernel's ptrace.h (which is > > apparently routine). > > > > A common backend header is created to hold common definitions, suitably > > namespaced, and with an appropriate header guard. > > > > See the commit message in patch 3 for further explanation of why this > > is needed. > > > > Because of the non-trivial header guard in the new sve_context.h, patch > > 1 adds support to headers_install.sh to munge #if defined(_UAPI_FOO) in > > a similar way to the current handling of #ifndef _UAPI_FOO. > > > > thanks for doing this. > > the patches fix the gdb build issue on musl libc with an > additional gdb patch: > https://sourceware.org/ml/gdb-patches/2018-12/msg00152.html > (in userspace i'd expect users relying on signal.h providing > whatever is in asm/sigcontext.h.) > > i think sve_context.h could be made to work with direct include, > even if that's not useful because there is no public api there. > (and then you dont need the first patch)
My general view is that if you want the sigframe types userspace should usually include <ucontext.h> and refer to mcontext_t. Because the prototype for sa_sigaction() specifies a void * for the ucontext argument, I've generally assumed that <signal.h> is not sufficient to get ucontext_t (or mcontext_t) (but maybe I'm too paranoid there). Non-POSIX-flavoured software might include <asm/sigcontext.h> directly. In glibc/musl libc will that conflict with <signal.h>, or can the two coexist? Cheers ---Dave
