[Crash-utility] 答复: Re: [patch]Crash can't process xen dump core files larger that 4GB.

Hi all, There is a bug when using crash to process the xen domU dump core that larger that 4GB(it is found at processing a 10GB guest core dump file). crash reporting this errors: crash: cannot find mfn 8392757 (0x801035) in page index crash: cannot read/find cr3 page this is caused by a var overflow,in the structure of typedef struct xc_core_header { unsigned int xch_magic; unsigned int xch_nr_vcpus; unsigned int xch_nr_pages; unsigned int xch_ctxt_offset; unsigned int xch_index_offset; unsigned int xch_pages_offset; } xc_core_header_t; the xch_ctxt_offset,xch_index_offset and xch_pages_offset mean the offsets in the core dump file , when it is defined as unsingend long ,that means the file can't be more that 4GB,so when processing with core dump files that more than 4GB may have error (I encountered overflow on that 10GB file),so changing those offset vars to unsigned long ,make sure crash can seek to the right position. btw,please reply directly to me ,I am not in the mail list. Signed-off-by: Xiaowei Hu <xiaowei.hu(a)oracle.com&gt; diff -up crash-5.0.0/xendump.h.org crash-5.0.0/xendump.h --- crash-5.0.0/xendump.h.org 2010-02-04 03:48:04.000000000 +0800 +++ crash-5.0.0/xendump.h 2010-02-04 05:41:27.000000000 +0800 @@ -28,9 +28,9 @@ typedef struct xc_core_header { unsigned int xch_magic; unsigned int xch_nr_vcpus; unsigned int xch_nr_pages; - unsigned int xch_ctxt_offset; - unsigned int xch_index_offset; - unsigned int xch_pages_offset; + unsigned long xch_ctxt_offset; + unsigned long xch_index_offset; + unsigned long xch_pages_offset; } xc_core_header_t; struct pfn_offset_cache {

First question -- are you saying that the change above works for you?

And second -- in your dumpfile, even with 10GB of memory, wouldn't the base offset value of all three indexes still fit well below the 4GB mark?

The xc_core_header in crash is a copy of that found in "tools/libxc/xenctrl.h", and is presumptively the beginning/header of the dumpfile. And so making the wholesale change above breaks all earlier (?) versions.

But what is confusing is that the latest/final version of "xenctrl.h" used in RHEL5 (3.0.3 vintage), as well as the current version in Fedora (3.4.0-2.fc12) still use unsigned int offsets, and I just checked with one of our xen masters, and the Xensource git tree also still has unsigned int values in the header data structure:

typedef struct xc_core_header { unsigned int xch_magic; unsigned int xch_nr_vcpus; unsigned int xch_nr_pages; unsigned int xch_ctxt_offset; unsigned int xch_index_offset; unsigned int xch_pages_offset; } xc_core_header_t;

#define XC_CORE_MAGIC 0xF00FEBED #define XC_CORE_MAGIC_HVM 0xF00FEBEE

Are your xen userspace tools an Oracle hybrid?

Dave