On 11/03/13 12:56, Vineet Gupta wrote: > 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. Agreed. Note that in uClibc, 64bit arches (excl alpha/mips for some reason) were already defining __IPC_64 as 0, so there's some precedent for it working the way it does. Cheers James -- 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
