transmit to 32bits or 64bits

[Enrique Abad Tomapasca]

what is the difference, advantage or disadvantage to transmit to 32bits or 64bits. The hardware and software transmit to 34 or 64, one depends on the other?

[Steven E. Protter]

32 bit software is limited to 2 GB of addressable memory in hpux without memory windows.

64 bit has a higher address limit. The newer HP-UX OS's are 64 bit only but will support 32 bit apps.

SEP

[rick jones]

In this context I assume 32 and 64 bit refer to the size of addresses - aka pointers.

IIRC, with some special compile/linker/chatr options, a 32-bit app on UX can get to 3.something GB but indeed the best thing to do for such apps as need that much memory is to transition them to 64-bit.

Hardware is the hard requirement. To run 64-bit software, one needs "64-bit" hardware. To run 64-bit applications, the kernel must be 64-bit. As mentioned, today, the OS (kernel) on 64-bit hardware is 64 bit. A 64-bit UX kernel can run 32-bit applications.

The advantage of 64-bit is greater addressability. The disadvantage is that variables of type pointer and of type long are now twice the size they used to be, so depending on the application, the memory and especially cache footprint will increase.

The mode where pointers and longs are 64 bit is called "LP64" Longs, Pointers 64-bit. 32 bit under HP-UX is ILP32 - Ints, Longs, Pointers 64-bit. In LP64, ints remain 32-bits.

Even if you do not have applications that need more than 2 or 3GB of RAM you should probably start working on a 64-bit transition. Applications will have their needs grow, and having your applications "64-bit clean" may save you a great deal of time and effort down the road when the crunch comes. Off of devresource.hp.com there are likely links describing the offerings to help check your sources to see if they are ready for 64-bit. And you can IIRC try a test compilation for 64-bit even on a 32-bit system - you can compile, but you cannot run.

So, no reason to not get started :)