From mboxrd@z Thu Jan 1 00:00:00 1970 From: dbrace Subject: kmap_atomic issue with SLES11SP1 32bit XEN driver code Date: Wed, 07 Dec 2011 15:47:57 -0600 Message-ID: <4EDFDF0D.2020104@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org kernel: Linux 360 2.6.32.12-0.7-xen #1 SMP 2010-05-20 11:14:20 +0200 i686 i686 i386 GNU/Linux I am having issues with some code that uses kmap_atomic(). I am getting: BUG: unable to handle kernel paging request at 23a1a000 (which is the address returned from kmap_atomic().) The same code works when running on non-XEN 32bit kernels so I am wondering why this does not work under XEN kernels. Is there a different approach that I need to take for 32bit XEN kernels? I really only need to do this code segment if the memory address is a high memory address. Is there a MACRO or function that can help me determine this? Here is a code snippet: void *linux_vaddr = NULL; /* kmapped temporary virtual address */ int linux_page_offset = 0; /* offset in page */ int count = 0; /* bytes left to transfer */ int left = byte_count; /* number of bytes left to transfer */ int memcpysize = 0; /* current size to transfer */ struct page *linux_page = NULL; /* calculated page */ int kmap_flags = 0; linux_page = __pfn_to_page(physical_address >> PAGE_SHIFT); linux_page_offset = (physical_address & 0x0000000000000FFFULL); memcpysize = min((PAGE_SIZE - linux_page_offset), left); kmap_flags = KM_USER0; linux_vaddr = kmap_atomic(linux_page, kmap_flags) + linux_page_offset; printk("%s: called kmap_atomic, " "calling memcpy linux_vaddr = 0x%x virt_address = 0x%x count = 0x%x\n", __func__, linux_vaddr, virt_address, count); /* * Either need to copy to a kmapped destination * or a kmapped source. */ if (type == 0) // Write to s/g element, dest virtual addr was known. memcpy((void *)virt_address+count, (void *)linux_vaddr, memcpysize); else // Source virt. address was known. memcpy((void *)linux_vaddr, (void *)virt_address+count, memcpysize); printk("OS_Linux32_Xfer_SG_Page: calling kunmap_atomic, " "calling memcpy linux_vaddr = 0x%lx\n", linux_vaddr); kunmap_atomic(linux_vaddr, kmap_flags); -- Don Brace SPSN Linux Development Hewlett-Packard Company