On Sat, 18 Aug 2012 05:39:07 -0400 (EDT), Philipp Kern wrote: > On Fri, Aug 17, 2012 at 07:11:26PM +0900, Satoru KURASHIKI wrote: >> This segfault occurs only on s390x, so I guess it is some of platform >> specific one. Are there any pattern or best practice about such problems? > > Casts of pointers usually are a problem. Like casting size_t* to int* > and vice versa. > > Kind regards > Philipp Kern > > PS: The liberal use of casts from (unsigned) char* to int* does not make me > that happy. Like «return (int *)"";»…
On a related subject, Satoru, s390 and s390x are "big-endian" machine architectures, whereas most computers, including i386 and amd64, are "little-endian" architectures. That is to say that s390 and s390x store integers in storage with the high-order byte at the low address and the low-order byte at the high address. For example, the decimal number 19,088,743, when converted to a 32-bit binary integer and expressed in hexadecimal notation, is 01234567. When that number is in a register, both on amd64 and s390x, it is stored with the high-order byte on the left, the next high-order byte adjacent to that, and so on, with the low-order byte on the right. But when the number is stored into RAM, the two architectures do it differently. On s390x, the number is stored in big-endian format, with the high-order byte at the lowest storage address and the low-order byte at the highest storage address: 01 23 45 67. amd64 stores the bytes in RAM in reverse order: 67 45 23 01. This is "little-endian" format. Sometimes hidden assumptions of little- endian format creep into programs that cause them to not work properly on s390x. -- .''`. Stephen Powell : :' : `. `'` `- -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/1309768158.513538.1345292571615.javamail.r...@md01.wow.synacor.com
