On Thu, Jun 18, 2015 at 12:58 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Thursday 18 June 2015 09:52:36 Michael Kerrisk wrote: >> [CC += David] >> >> On 2 June 2015 at 18:36, Andy Lutomirski <luto@xxxxxxxxxx> wrote: >> > include/uapi/linux/signal.h starts with: >> > >> > #ifndef _UAPI_LINUX_SIGNAL_H >> > #define _UAPI_LINUX_SIGNAL_H >> > >> > #include <asm/signal.h> >> > #include <asm/siginfo.h> >> > >> > This causes it to include <asm/signal.h>, which is not the same thing >> > as <uapi/asm/signal.h>. Changing that will break userspace use of >> > this header, though, as the uapi/ won't get removed. >> > >> > What's the correct fix? This is causing trouble with a UML build for me. >> >> Perhaps David has some insight, since he architected the original UAPI split. > > The uapi headers are installed without the uapi prefix. This means > that inside of the kernel, we get > > > linux/signal.h > -> uapi/linux/signal.h > -> asm/signal.h > -> uapi/asm/signal.h > > while in the installed headers we just get > > linux/signal.h > -> asm/signal.h > > This all looks right to me: user space only sees the exported portions > under the traditional names, while the kernel sees both the kernel-side > and user-side definitions from the same path. > It seems counterintuitive and error-prone to me that including <uapi/linux/signal.h> would pull in non-UAPI asm/signal.h declarations in the kernel but not when used from userspace. It would make it very easy to break the header such that it's only broken in a userspace context. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
