Hi Al, 2012/10/17 Al Viro <viro@xxxxxxxxxxxxxxxxxx>: > On Wed, Oct 17, 2012 at 05:07:03PM +0100, Al Viro wrote: >> What happens during boot is this: >> * init_task (not to be confused with init) is used as current during >> infrastructure initializations. Once everything needed for scheduler and >> for working fork is set, we spawn two threads - future init and future >> kthreadd. The last thing we do with init_task is telling init that kthreadd >> has been spawned. After that init_task turns itself into an idle thread. >> * future init waits for kthreadd to be spawned (it would be more >> natural to fork them in opposite order, but we want init to have PID 1 - >> too much stuff in userland depends on that). Then it does the rest of >> initialization, including setting up initramfs contents. And does >> kernel_execve() on /init. Note that this is a task that had been created >> by kernel_thread() and is currently in function called from >> ret_from_kernel_thread(). Its kernel stack has been set up by copy_thread(). >> That's where pt_regs need to be set up; note that they'll be passed to >> start_thread() before you return to userland. If there are any magic bits >> in pt_regs needed by return-from-syscall code, set them in kthread case of >> copy_thread(). > > PS: I suspect that we end up with the wrong value in childregs->msr; > start_thread() only add MSR_UMS there. I'd suggest running the kernel > with these patches + printk childregs->msr the very first time start_thread() > is called and see what it prints, then working kernel + such printk and > compare the results... sorry for taking this so long. I have looked at it and fix it. Here is the branch based on rc5 (information below) and here is giweb. http://developer.petalogix.com/git/gitweb.cgi?p=linux-2.6-microblaze.git;a=shortlog;h=refs/heads/viro/arch-microblaze-rc5 I have also looked at your sys_fork / sys_vfork / sys_clone unification and I have fixed it for Microblaze. Also I have done some tests on it for sure. I would add sys_execve/kernel_execve/kernel_thread patches to my next branch. Are you OK with that? Do you need to test anything else for MB? Thanks, Michal The following changes since commit 77b67063bb6bce6d475e910d3b886a606d0d91f7: Linus Torvalds (1): Linux 3.7-rc5 are available in the git repository at: git://git.monstr.eu/linux-2.6-microblaze.git viro/arch-microblaze-rc5 Al Viro (5): microblaze: switch to generic kernel_thread() microblaze: switch to generic kernel_execve() microblaze: switch to generic sys_execve() generic sys_fork / sys_vfork / sys_clone microblaze: switch to generic fork/vfork/clone Michal Simek (3): microblaze: Fix bug with schedule_tail microblaze: Define current_pt_regs microblaze: Remove BIP from childregs arch/Kconfig | 11 ++++ arch/microblaze/Kconfig | 3 + arch/microblaze/include/asm/processor.h | 10 +--- arch/microblaze/include/asm/unistd.h | 6 ++ arch/microblaze/kernel/entry-nommu.S | 20 +++----- arch/microblaze/kernel/entry.S | 57 ++++------------------- arch/microblaze/kernel/process.c | 77 ++++++++++--------------------- arch/microblaze/kernel/sys_microblaze.c | 53 --------------------- arch/microblaze/kernel/syscall_table.S | 6 +-- include/asm-generic/syscalls.h | 7 +-- kernel/fork.c | 43 +++++++++++++++++ 11 files changed, 111 insertions(+), 182 deletions(-) -- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/ Microblaze U-BOOT custodian -- 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
