Re: Itanium size-related tests
At 2002/7/29 11:25-0700 Wichmann, Mats D writes:
>
> (a) What's the right value for VSRT_ADDR_SPACE_PAGES ?
> This is a configuration parameter that goes in
> TESTROOT/tetexec.cfg and is used by a couple of
> (currently failing) mmap tests
The current value of VSRT_ADDR_SPACE_PAGES has been tuned for 32 bit
userspace. The right value to use was found mostly through a bit of
experimentation. The following excerpt from the config file should
help you work out what value to use:
# The maximum size of a process' address space, in pages. This value
# is used in mmap testing (mmap 26 and 31 and mmap_P 29 and 34) to
# verify ENOMEM is returned when memory allocation is not possible
# due to address space boundaries. On some systems where this value
# is very large, using the actual value may cause mmap to fail with
# an invalid value error. These tests are constructed so that they
# completely validate their assertions using any value between 1/2 the
# size of the address space and its full size can be used, and in this
# circumstance a smaller value in this range should be configured here.
We'll need to change the test suite setup so the value can be set on a
per-architecture basis.
> (b) Why does SSIZE_MAX end up set to the size of
> an int, rather than a 64-bit quantity, on standard
> GNU/Linux header files? This one affects the
> calculation done by failing readv and writev tests
> which are trying to overflow an ssize_t to test the
> error code. But the don't come close, since the
> calulation based on SSIZE_MAX builds 1024 iovs
> of 2,098,176 bytes.
The kernel readv/writev code which checks this has changed quite a bit
between 2.4 and 2.5. It used to try (but I think it was wrong) to test
when the total read length would overflow a 32 bit int. The 2.5
behaviour checks for overflow of ssize_t and presumably libc now has
to catch up. I've asked glibc IA64 guy to look at it.
Regards,
Chris
--
cyeoh@au.ibm.com
IBM OzLabs Linux Development Group
Canberra, Australia
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