question about nopage sample code
in ldd3 no page is implemented as the code posted below (page 428).
can someone explain why should we subtract vma->vm_start?
struct page *simple_vma_nopage(struct vm_area_struct *vma,
unsigned long address, int *type)
{
struct page *pageptr;
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
unsigned long physaddr = address - vma->vm_start + offset; // why
should we subtract vma->vm_start ?
unsigned long pageframe = physaddr >> PAGE_SHIFT;
if (!pfn_valid(pageframe))
return NOPAGE_SIGBUS;
pageptr = pfn_to_page(pageframe);
get_page(pageptr);
if (type)
*type = VM_FAULT_MINOR;
return pageptr;
}
thank you
Ali Aminian.
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Re: How to dump user space stack from kernel space
On Tue, Feb 21, 2017 at 03:09:30PM +, Abhay Koralli wrote: > Hi, > > We want to get the user space stack trace from the kernel space. Is there any > easy way to dump the same ? What exact problem are you trying to solve that getting a random userspace callstack is needed from within the kernel? thanks, greg k-h ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Cannot activate multiple CPUs.
Is there a trick to bringing up multiple CPUs on an SOC? My kernel is not bringing up secondary CPUs. Running a kernel compiled from v4.10 sources on an LS1046A reference board. Support for this platform only arrived in the mainline sources in v4.10, so it is pretty new, and there are clearly differences from the vendor supplied SDK sources. Configured with generic arm64 defconfig. Loading the kernel via `booti` in u-boot. Provided fsl-ls1046a-rdb.dtb as the device tree. Console log indicates only a single CPU is available. [0.083735] EFI services will not be available. [0.096301] smp: Bringing up secondary CPUs ... [1.141306] CPU1: failed to come online [1.145159] CPU1: failed in unknown state : 0x0 [2.202164] CPU2: failed to come online [2.206016] CPU2: failed in unknown state : 0x0 [3.263021] CPU3: failed to come online [3.266873] CPU3: failed in unknown state : 0x0 [3.271449] smp: Brought up 1 node, 1 CPU Is it possible that multiple cores are not supported in the mainline code? Or am I missing some piece of configuration that would bring up multiple cores? Thanks in advance, - Chris ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
