Re: [uml-devel] missing asm/user.h

[Jeff Dike <jdike@addtoit.com>]

On Sat, Mar 24, 2007 at 11:36:28PM -0400, Daniel Gryniewicz wrote:
> Update:  <asm/elf.h> isn't there either, but <sys/user.h> includes
> user_regs_struct, so that's sufficient for this problem.

Hummph, I hope that's true of every other distro that people use UML on.

> The next problem is lack of <asm/page.h>.  Most files failing to build
> with it can simply have it removed.  I've temporarily replaced PAGE_SIZE
> with sysconf(_SC_PAGESIZE) for now, and we'll see how that works.

Send patches.

BTW, the important thing about PAGE_SIZE in the userspace side of UML
is not that it be the same as sysconf(_SC_PAGESIZE) but that it match
the value of PAGE_SIZE in the kernelspace side.  Obviously, these
values will all be the same everywhere that we care about now, but I
can think of one or two situations where it would matter.  On an
architecture with a variable page size, the UML kernel can have a
PAGE_SIZE of 64K but the host's sysconf can report a page size of 4K.
In this case, it's important that PAGE_SIZE in UML userspace code be
64K.

So, there's UM_KERN_PAGE_SIZE in kern_constants.h which is derived
from the kernel's PAGE_SIZE and is usable in userspace files.  Use
that instead of sysconf().

				Jeff

-- 
Work email - jdike at linux dot intel dot com

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