From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 27 Feb 2002 09:47:40 -0800 From: Mark Charlebois To: Goddeeris Frederic Cc: "'linuxppc-embedded@lists.linuxppc.org'" , "'inuxppc-dev@lists.linuxppc.org'" Subject: Re: DECLARE_WAIT_QUEUE_HEAD; structure badly initialized... Message-ID: <20020227094740.A12123@qualcomm.com> References: <6B546A602AD2D211BFF00008C7A4288905843FFE@hrtades2.atea.be> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <6B546A602AD2D211BFF00008C7A4288905843FFE@hrtades2.atea.be>; from Frederic.Goddeeris@siemens.atea.be on Wed, Feb 27, 2002 at 10:30:32AM +0100 Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: I have had similar problems with static/global initialization in USB module code. A wait_queue_head was not properly initialized and we had to re-initialize it in module_init(). I also noticed that the static text strings (.rodata segment ) were not displayed properly in /proc/bus/usb/drivers for the USB modules but they were correct when not compiled as a module. I have only observed this problem with modules and assumed it might have something to do with the dcache and module initialization. I haven't had a chance to investigate it further yet... although I am glad to finally see that someone else has experienced something similar! We are using a patched HHL2.0 for walnut kernel (2.4.2 + USB from 2.4.17). - Mark * Goddeeris Frederic (Frederic.Goddeeris@siemens.atea.be) [020227 01:36]: > > Hi, > > I write in my code: > > This should initialize the structure so that .task_list.next and > .task_list.prev point ot its own .task list, but the pointers seem to point > 4 bytes to far... > > I added this test-code: > > DEBUG("TEST: %x %x\n",&f_SCBlockReadQueue.task_list, > f_SCBlockReadQueue.task_list.next); > f_SCBlockReadQueue.task_list.next = &f_SCBlockReadQueue.task_list; > f_SCBlockReadQueue.task_list.prev = &f_SCBlockReadQueue.task_list; > DEBUG("TEST: %x %x\n",&f_SCBlockReadQueue.task_list, > f_SCBlockReadQueue.task_list.next); > > And this results in: > FPGADrv >> TEST: c3044754 c3044758 ==> WRONG > FPGADrv >> TEST: c3044754 c3044754 ==> CORRECT > > After the code corrected the the pointers, the driver starts behaving as > expected. > > The preprosessor converts "DECLARE_WAIT_QUEUE_HEAD(f_SCBlockReadQueue);" to: > wait_queue_head_t f_SCBlockReadQueue = { lock: (spinlock_t) > { 0 } , task_list: { &(f_SCBlockReadQueue).task_list, > &(f_SCBlockReadQueue).task_list }, } ; > This looks ok to me > > When using > init_waitqueue_head(&f_SCBlockReadQueue); > it works. > > So when the structure is initialized in code it works nicely, when it is > initialized at compile-time it fails. Does anybody know why? > > The compiler is 2.95.3 (HHL2.0) > > Thanks, > Frederic > > ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/