Re: 2.6.11.8 + UML/x86_64 (2.6.12-rc3+) = oops

[Al Viro <viro@parcelfarce.linux.theplanet.co.uk>]

On Sun, May 08, 2005 at 07:10:44AM +0100, Al Viro wrote:
> 	r) when built static, kernel dies ugly death with
> #0  0x00000000601e4178 in ptmalloc_init () at swab.h:134
> #1  0x00000000601e4034 in malloc_hook_ini () at swab.h:134
> #2  0x00000000601e1698 in malloc () at swab.h:134
> #3  0x00000000602068ee in _dl_init_paths () at swab.h:134
> #4  0x00000000601eba45 in _dl_non_dynamic_init () at swab.h:134
> #5  0x00000000601ebc60 in __libc_init_first () at swab.h:134
> #6  0x00000000601cfa4f in __libc_start_main () at swab.h:134
> #7  0x000000006001202a in _start () at proc_fs.h:183
> as stack trace.  Buggered offsets in uml.lds, perhaps?

Apparently solved by adding .tdata and .tbss to uml.lds.S.  That change does
not give any visible regression on i386.

	s) i386 TT-only won't compile, due to mispaced include in
sysdep/ptrace.h (under ifdef for skas).  Trivial fix apparently gets it
to work correctly.  Which is surprising - when running that sucker on
amd64 we get zero from
        *host_size_out = ROUND_4M((unsigned long) &arg);
Of course, the real size rounded up to 4M is 4Gb there - 32bit tasks do not
have to share the lower 4Gb of address space with the kernel.  Looks like
we survive, though - it boots and apparently works both on i386 and (as
32bit process) on amd64.
	t) amd64 TT-only builds just fine, but gets buggered due to
mismatch between CONFIG_TOP_ADDR and start address - we get *both* set
to 0x60000000, which is obviously b0rken and doesn't match the old
code, while we are at it.  We want TOP_ADDR at 0x80000000 to match start
address.
	u) amd64 TT is _still_ buggered due to unmap_fin.o attempts at
magic.  errno sits in TLS for amd64, so unmap_fin.o gets very interesting
stuff leaking from libc and messing the link.  IMO that should be dealt
with by brute force; namely, unmap-$(SUBARCH).S instead of trying to
play games with pulling stuff from libc.a.  For fsck sake, we are just
making 3 syscalls there and switcheroo() is as low-level as it gets...
Will post once that's done...