Hello, everyone. I use alloc_bootmem() in profile.c to allocate a big memory at function profile_init(), how I know whether it is success? The following is my code: // at kernel/profile.c ctxsw_A = (struct ctxsw_rec *)alloc_bootmem(sizeof(struct ctxsw_rec)*CTXSW); ctxsw_rec is a struct which declared in include/linux/profile.h, CTXSW = 4>>10
On Fri, Apr 15, 2011 at 1:49 PM, javaweb zhang <javawebzwp@gmail.com> wrote:
Hello, everyone. I use alloc_bootmem() in profile.c to allocate a big memory at function profile_init(), how I know whether it is success? The following is my code: // at kernel/profile.c ctxsw_A = (struct ctxsw_rec *)alloc_bootmem(sizeof(struct ctxsw_rec)*CTXSW); ctxsw_rec is a struct which declared in include/linux/profile.h, CTXSW = 4>>10
4 >> 10 equals to zero. I think that it's your typo error. If you meet failure on allocating bootmem, kernel will panic.
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Hi, On Thu, Apr 14, 2011 at 10:49 PM, javaweb zhang <javawebzwp@gmail.com> wrote:
Hello, everyone. I use alloc_bootmem() in profile.c to allocate a big memory at function profile_init(), how I know whether it is success? The following is my code: // at kernel/profile.c ctxsw_A = (struct ctxsw_rec *)alloc_bootmem(sizeof(struct ctxsw_rec)*CTXSW); ctxsw_rec is a struct which declared in include/linux/profile.h, CTXSW = 4>>10
Looking at the source code for alloc_bootmem, it returns a NULL pointer (which is what most allocators do when the allocation fails). It appears that it will hit a panic first though, so you may never get to the receiving the NULL. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com
Hi, Thank you. I have found the main reason for my problem. alloc_bootmem() must use after init_bootmem_node() and before free_all_bootmem(), but profile_init() is executed after free_all_bootmem(), so it could not alloc the memory what I want. 2011/4/15 Dave Hylands <dhylands@gmail.com>
Hi,
On Thu, Apr 14, 2011 at 10:49 PM, javaweb zhang <javawebzwp@gmail.com> wrote:
Hello, everyone. I use alloc_bootmem() in profile.c to allocate a big memory at function profile_init(), how I know whether it is success? The following is my code: // at kernel/profile.c ctxsw_A = (struct ctxsw_rec *)alloc_bootmem(sizeof(struct ctxsw_rec)*CTXSW); ctxsw_rec is a struct which declared in include/linux/profile.h, CTXSW = 4>>10
Looking at the source code for alloc_bootmem, it returns a NULL pointer (which is what most allocators do when the allocation fails). It appears that it will hit a panic first though, so you may never get to the receiving the NULL.
-- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com
participants (3)
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Dave Hylands -
Haojian Zhuang -
javaweb zhang