svn commit: r291937 - in head: lib/libc/aarch64/sys lib/libc/arm/sys sys/arm/arm sys/arm/include sys/arm64/arm64 sys/arm64/include sys/conf sys/kern

[Konstantin Belousov]

On Thu, Dec 24, 2015 at 08:40:42AM -0700, Ian Lepore wrote:
> On Mon, 2015-12-07 at 12:20 +0000, Konstantin Belousov wrote:
> > Author: kib
> > Date: Mon Dec  7 12:20:26 2015
> > New Revision: 291937
> > URL: https://svnweb.freebsd.org/changeset/base/291937
> > 
> > Log:
> >   Add support for usermode (vdso-like) gettimeofday(2) and
> >   clock_gettime(2) on ARMv7 and ARMv8 systems which have architectural
> >   generic timer hardware. It is similar how the RDTSC timer is used in
> >   userspace on x86.
> >   
> >   Fix a permission problem where generic timer access from EL0 (or
> >   userspace on v7) was not properly initialized on APs.
> >   
> >   For ARMv7, mark the stack non-executable. The shared page is added for
> >   all arms (including ARMv8 64bit), and the signal trampoline code is
> >   moved to the page.
> >   
> >   Reviewed by:> 	> andrew
> >   Discussed with:> 	> emaste, mmel
> >   Sponsored by:> 	> The FreeBSD Foundation
> >   Differential revision:> 	https://reviews.freebsd.org/D4209
> 
> I've just discovered this change breaks buildworld on armv4/5 systems. 
>  Those systems don't have the counter hardware that can be read from
> userland (they don't have any common timer hardware at all, every
> system is different).  Also, they don't support the 'mrrc' instruction,
> so the buildworld fails to compile libc.

I tested the change with make universe.  Is the armv5 world included
into the make ?   If yes, there is something even more broken.

That said, the code in __vdso_gettime.c is unused om armv4/v5 since kernel
never directs libc to use a fast timecounter.  The routines could be left
undefined since they are declared weak, or the bodies could be stubbed out.
Anyway, to test, I should be able to compile libc for the target.

And, BTW, what is exactly your error message ?