Make sense. But there are other things in the UPAGES.
-Zhihui
On Mon, 23 Jul 2001, Weiguang SHI wrote:
> I guess this is it (/usr/src/sys/i386/i386/locore.s):
>
> 348 /* now running relocated at KERNBASE where the system is linked to
> run */
> 349 begin:
> 350 /* set up bootstrap stack */
> 351 movl _proc0paddr,%esp /* location of in-kernel
> pages */
> 352 addl $UPAGES*PAGE_SIZE,%esp /* bootstrap stack end
> location */
>
> where UPAGES is defined as 2 in
> /usr/src/sys/compile/MYKERNEL/machine/param.h
>
> 101 #define UPAGES 2 /* pages of u-area */
>
> Regards,
> Weiguang
>
> >From: Zhihui Zhang <[EMAIL PROTECTED]>
> >To: [EMAIL PROTECTED], "Eugene L. Vorokov" <[EMAIL PROTECTED]>
> >CC: [EMAIL PROTECTED]
> >Subject: Re: using syscalls in a module (stack problem ?)
> >Date: Mon, 23 Jul 2001 12:07:47 -0400 (EDT)
> >
> >
> >Just out of curiosity, Linux's kernel stack is one page. Where in the
> >kernel source code that says that we can have two pages instead of one
> >page kernel stack?
> >
> >-Zhihui
> >
> >
> >On Mon, 23 Jul 2001, Eugene L. Vorokov wrote:
> >
> > > > > I call this function with (curproc, PATH_MAX+1), and everything is
> >fine
> > > > > when I have just a few local variables defined in the caller (it all
> > > > > works on MOD_LOAD only). However, if I have 2 buffers, 4096 bytes
> >each,
> > > > > as local variables and then try to allocate userspace memory the
> >same
> > > > > way, kernel crashes - sometimes inside mmap(), sometimes a bit
> >later.
> > > > >
> > > > > Why could this happen ? Is it related to possible stack overflow ?
> > > >
> > > > Yes. The kernel stack is only two pages; you absolutely must not use
> > > > large local variables in the kernel.
> > >
> > > I see. But I still can define them using "static", right ?
> > >
> > > Regards,
> > > Eugene
> > >
> > >
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> > >
> >
> >
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>
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