Messages in this thread | | | Date | Fri, 18 Apr 2003 09:27:55 +0100 | From | Russell King <> | Subject | Kernel<->Userspace API issue |
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A problem has recently been reported on the ARM lists regarding RT signal handling. It appears that there is an issue between glibc and the kernel, in that glibc has a different idea of the layout of structures passed from the kernel than the kernel itself.
I think this is a case in point that our policy on "userspace must not include kernel headers" is completely wrong when it comes to user space interfaces. I believe we need is a clear set of defined user space interface headers which contain the definition of structures and numbers shared between user space and kernel space. ie, include/abi or some such.
No, glibckernheaders (or whatever it is) is NOT the solution - that just creates yet another set of header files to potentially go out of sync.
Comments?
On Thu, Apr 17, 2003 at 10:23:51PM -0400, Josh Fryman wrote: > any insights? is this an implementation issue, program error, or am i > missing some arm-centric trick? or am i just stupid and doing something > completely wrong?
Sigh. glibc seems to have a bug. This is the kernel's idea of ucontext:
struct ucontext { unsigned long uc_flags; struct ucontext *uc_link; stack_t uc_stack; struct sigcontext uc_mcontext; sigset_t uc_sigmask; /* mask last for extensibility */ };
and glibc's idea:
typedef struct ucontext { unsigned long int uc_flags; struct ucontext *uc_link; __sigset_t uc_sigmask; stack_t uc_stack; mcontext_t uc_mcontext; long int uc_filler[5]; } ucontext_t;
God knows where glibc got this from - it hasn't changed certainly since 2.2 kernels. I suspect glibc has been wrong for some time.
-- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html
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