Date: Wed, 8 Nov 2000 00:06:19 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Jacques Fourie <jacques4i@yahoo.com> Cc: freebsd-hackers@freebsd.org Subject: Re: kernel stack size? Message-ID: <200011080806.eA886Ju97762@earth.backplane.com> References: <20001108074327.28774.qmail@web3502.mail.yahoo.com>
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:
:Hi
:
:Thanks for your reply. I have two other questions
:regarding this matter.
:
:Would it be possible to extend the kernel stack?
:The reason is that some of the crypto and hashing
:algorithms use relatively large contexts which for
:performance reasons are currently allocated on the
:stack.
:
:If this is not a good idea, would it be possible to
:somehow allocate a block of memory on the heap and use
:this as a stack in my interrupt routine?
:
:regards,
:jacques
The simple answer is, no, it is not possible to extend
the kernel stack. You have to preallocate a block of
memory in the device open routine and associate it with
your softc structure. Your interrupt can reference the
memory that way. If the memory requirements are dynamic
in nature, the interrupt is the wrong place to be
trying to allocate and free memory. Preallocation will
not perform any worse then declaring an array on the stack
in terms of performance.
-Matt
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