Hi James, On Monday 11 March 2013 06:14 PM, James Hogan wrote: > Hi Vineet, > > On 11/03/13 12:29, Vineet Gupta wrote: >> On Wednesday 07 November 2012 07:43 PM, Arnd Bergmann wrote: >>> On Wednesday 07 November 2012, Vineet Gupta wrote: >>> >>>> + >>>> +config ARC >>>> + def_bool y >>>> + select ARCH_WANT_IPC_PARSE_VERSION >>>> + # ARC Busybox based initramfs absolutely relies on DEVTMPFS for /dev >>>> + # DEVTMPS in turn needs HOTPLUG >>>> + select DEVTMPFS if !INITRAMFS_SOURCE="" >>>> + select GENERIC_ATOMIC64 >>>> + select GENERIC_CLOCKEVENTS >>>> + select GENERIC_FIND_FIRST_BIT >>>> + # for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP >>>> + select GENERIC_IRQ_SHOW >>>> + select GENERIC_PENDING_IRQ if SMP >>>> + select GENERIC_SMP_IDLE_THREAD >>>> + select HAVE_GENERIC_HARDIRQS >>>> + select HOTPLUG if !INITRAMFS_SOURCE="" >>>> + select MODULES_USE_ELF_RELA >>> You should not need ARCH_WANT_IPC_PARSE_VERSION >> It seems, we have a small bug in sysV IPC. >> A lot of LTP tests have started failing on ARC 3.9-rc1 kernel due to absence of >> ARCH_WANT_IPC_PARSE_VERSION. >> >> I'm assuming that for newer arches, msgctl(2) and friends need to have need to >> have @cmd of type 0x01nn where 0x0100 is IPC_64. >> However for ! ARCH_WANT_IPC_PARSE_VERSION, ipc/util.h seems to be defining a dummy >> version of ipc_parse_version(), which doesn't strip out the 0x0100 from @cmds, >> causing the code to not enter the switch block in SYSCALL_DEFINE3(msgctl) making >> it fail. >> Adding the above item to arch/arc/Kconfig obviously fixes the breakage. >> >> It seems there is some bogosity in the way ipc_parse_version() is defined. Given >> the way it is used, to strip out the 0x0100 bit, it seems we always need the >> function variant - the IA-64 ish comment in there seems to be bit-rot. >> >> What do you think ? > FYI, for metag we assumed this was intentional and that IPC_64 shouldn't > be passed since it is the default behaviour for new arches. > You may find the following uClibc commit relevant: > http://git.uclibc.org/uClibc/commit/?id=6c2fa3451f35f8d78a31689044b2d19efa4eaca2 I've been using uClibc trunk - ported to ARC - for my testing, so I already have that change. Looking at Markos' uClibc branch he is indeed defining __IPC_64 to 0 in metag port. However, looking at the kernel code, it seems newer style is to do the other way round - i.e. pass 0x0100 in those cmds - unless the comments in there are bogus. include/uapi/linux/ipc.h /* * Version flags for semctl, msgctl, and shmctl commands * These are passed as bitflags or-ed with the actual command */ #define IPC_OLD 0 /* Old version (no 32-bit UID support on many architectures) */ #define IPC_64 0x0100 /* New version (support 32-bit UIDs, bigger message sizes, etc. */ So someone with more ABI wisdom needs to suggest what is the right approach. -Vineet -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
