M. Warner Losh wrote:
In message: <[EMAIL PROTECTED]>
Hans Petter Selasky <[EMAIL PROTECTED]> writes:
: So can someone have this fixed, or is there a reason not to fix it. The one
: who wrote the code has done the same mistake with every one of the
: bus_space_XXXX that does memory mapped I/O. It currently breaks my drivers.
One isn't supposed to call these routines with count == 0. One could
say your drivers are broken :-)
Back when these were written, small optimizations like this were made
to make things go faster. Now that cache sizes are bigger, a few
extra instructions likely wouldn't affect things too much. Best to
measure the effects of your proposed changes on real workloads...
Warner
I'm torn between saying, "this is the kernel and the kernel is an
unforgiving mistress," and "defensive programming is good." We still
have viable and popular platforms that are based on i486, so I'd rather
not see us unwind the small optimizations that are still valid there.
Scott
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