On Thu, 2009-05-28 at 18:39 +0200, Philippe Gerum wrote:
> On Thu, 2009-05-28 at 11:59 -0400, Andreas Glatz wrote:
> > Hi,
> >
> > We have to start 40+ Xenomai tasks in kernel space.
> > We want to allocate at least 4kbyte of stack memory
> > for each of them. So we need the stack heap size
> > to be more than 160kbyte.
> >
> > In the documentation it says that the total
> > stack heap size cannot be more than 128kbyte
> > (the limit of kmalloc).
>
> Could you point me at that doc? TIA,
>
> >
> > Now my idea is to modify the Xenomai code to have
> > more than one stack heaps. So when I'm running out
> > of space in one heap I can switch to the next heap...
> >
> > Is there an easier way to increase the max. stack heap size?
> >
>
> See CONFIG_XENO_OPT_SYS_STACKPOOLSZ, nucleus configuration menu.
I found this in kernel/xenomai/nucleus/Kconfig :
config XENO_OPT_SYS_STACKPOOLSZ
depends on XENO_GENERIC_STACKPOOL
int "Size of the private stack pool (Kb)"
default 32
range 0 128
help
On this architecture, kernel-based Xenomai threads get the
stack space they need from a private memory pool. If you
don't start any kernel-based thread (i.e. no RTDM driver
thread, and no real-time task created from an application
embodied into a kernel module), you may leave a zero value for
this option. The size is expressed in Kilobytes.
And if you follow the CONFIG_XENO_OPT_SYS_STACKPOOLSZ macro
you eventually end up at this comment in kernel/xenomai/nucleus/pod.c :
/*
* We have to differentiate the system heap memory from the
* pool the kernel thread stacks will be obtained from,
* because on some architectures, vmalloc memory may not be
* accessed while running in physical addressing mode
* (e.g. exception trampoline code on powerpc with standard
* MMU support - CONFIG_PPC_STD_MMU). Meanwhile, since we want
* to allow the system heap to be larger than 128Kb in
* contiguous memory, we can't restrict to using kmalloc()
* memory for it either. Therefore, we manage a private stack
* pool for kernel-based threads which will be populated with
* the kind of memory the underlying arch requires, still
* allowing the system heap to rely on a vmalloc'ed segment.
*/
heapaddr = xnarch_alloc_stack_mem(CONFIG_XENO_OPT_SYS_STACKPOOLSZ *
1024);
Andreas
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