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authorJeff Dike <jdike@addtoit.com>2008-02-08 04:22:07 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 09:22:42 -0800
commit536788fe2d28e11db6aeda74207d95d750fb761f (patch)
tree73df2d3a46c542c71d3a84c20c8fd1ce617386a3 /arch/um/os-Linux/sys-x86_64/task_size.c
parentCONFIG_HIGHPTE vs. sub-page page tables. (diff)
downloadlinux-dev-536788fe2d28e11db6aeda74207d95d750fb761f.tar.xz
linux-dev-536788fe2d28e11db6aeda74207d95d750fb761f.zip
uml: runtime host VMSPLIT detection
Calculate TASK_SIZE at run-time by figuring out the host's VMSPLIT - this is needed on i386 if UML is to run on hosts with varying VMSPLITs without recompilation. TASK_SIZE is now defined in terms of a variable, task_size. This gets rid of an include of pgtable.h from processor.h, which can cause include loops. On i386, task_size is calculated early in boot by probing the address space in a binary search to figure out where the boundary between usable and non-usable memory is. This tries to make sure that a page that is considered to be in userspace is, or can be made, read-write. I'm concerned about a system-global VDSO page in kernel memory being hit and considered to be a userspace page. On x86_64, task_size is just the old value of CONFIG_TOP_ADDR. A bunch of config variable are gone now. CONFIG_TOP_ADDR is directly replaced by TASK_SIZE. NEST_LEVEL is gone since the relocation of the stubs makes it irrelevant. All the HOST_VMSPLIT stuff is gone. All references to these in arch/um/Makefile are also gone. I noticed and fixed a missing extern in os.h when adding os_get_task_size. Note: This has been revised to fix the 32-bit UML on 64-bit host bug that Miklos ran into. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um/os-Linux/sys-x86_64/task_size.c')
-rw-r--r--arch/um/os-Linux/sys-x86_64/task_size.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/um/os-Linux/sys-x86_64/task_size.c b/arch/um/os-Linux/sys-x86_64/task_size.c
new file mode 100644
index 000000000000..fad6f57f8ee3
--- /dev/null
+++ b/arch/um/os-Linux/sys-x86_64/task_size.c
@@ -0,0 +1,5 @@
+unsigned long os_get_task_size(unsigned long shift)
+{
+ /* The old value of CONFIG_TOP_ADDR */
+ return 0x7fc0000000;
+}