[Linux-ia64] mmap failure

[Linux-ia64] mmap failure

[Ronald Veldema]

Hi all,
    it looks like mmap fails when calling mmap as:

    mmap(0x30000066910000,
                16384,
            PROT_READ | PROT_WRITE,  
          MAP_FIXED,MAP_PRIVATE,
       fd,0x30000066910000);

Other addresses are ok. It fails with EINVAL.
Is 0x30000... reserved for the kernel ?
R.
      

RE: [Linux-ia64] mmap failure

[Luck, Tony]

>     it looks like mmap fails when calling mmap as:
> 
>     mmap(0x30000066910000,
>                 16384,
>             PROT_READ | PROT_WRITE,  
>           MAP_FIXED,MAP_PRIVATE,
>        fd,0x30000066910000);
> 
> Other addresses are ok. It fails with EINVAL.
> Is 0x30000... reserved for the kernel ?

0x30000066910000 is too far from a region boundary.

Although Itanium 2 supports a full 64-bit virtual
address space, Linux can't map objects to any place
in the 64-bit range because with a 3-level page
table it can't use all of the address bits.

The areas that can be mapped by Linux are at the
bottom and top of each Itanium "region" (top three
bits of the virtual address are the region number).

-Tony

Re: [Linux-ia64] mmap failure

[David Mosberger]

>>>>> On Tue, 27 May 2003 21:55:05 +0200, Ronald Veldema <veldema@cs.fau.de> said:

  Ronald> Hi all, it looks like mmap fails when calling mmap as:

  Ronald>     mmap(0x30000066910000, 16384, PROT_READ | PROT_WRITE,
  Ronald> MAP_FIXED,MAP_PRIVATE, fd,0x30000066910000);

  Ronald> Other addresses are ok. It fails with EINVAL.  Is
  Ronald> 0x30000... reserved for the kernel ?  R.

No, but it's not mappable by the Linux kernel.

The details are in the VM chapter of my book (Figure 4.13, in
particular).  If you don't want to buy the book just because of this,
you're in luck: the VM chapter happens to be the sample chapter
available at:

	http://www.lia64.org/book/

Hope this helps,

	--david