Kumba wrote:
Initially, booting a straight git checkout on an IP32 will cause it to
prom crash, usually somewhere in between init_bootmem() and
init_bootmem_core(). I bisected git to trace this back to one of the
inital __pa() introduction patches from commit d4df6d4 (get ride of
CPHYSADDR()). It actually appears that the actual commit that broke
things was 620a480 (Make __pa() aware of XKPHYS/CKSEG0 address mix for
64 bit kernels).
The [short-term] fix highlighted by Ilya is to make __pa()
unconditionally be defined to "((unsigned long)(x) < CKSEG0 ?
PAGE_OFFSET : CKSEG0)"; Discovered by building IP32 with
CONFIG_BUILD_ELF64=n.
Normally, this shouldn't be possible, as CONFIG_BUILD_ELF64=n was
originally only allowed by using the old o64 hack, which has
subsequently died and been replaced with the newer -msym32 form. As far
as I know, CONFIG_BUILD_ELF64 is apparently supposed to be removed at
some point in the future, since I believe it existed only for quirky
64bit-in-32bit kernels for IP22 and more commonly, IP32. From 2.6.17
onwards, I've been building IP32 kernels with CONFIG_BUILD_ELF64=y and
using gcc-4, and haven't had problems up until now.
Anyways, I'm not sure if this is an IP32-specific oddity or not
(probably is), but it needs the define highlighted above to work
properly. Plain PAGE_OFFSET won't work for these machines. Given the
same trick os -msym32 is used for the rare IP22 64bit kernel, I would
not be surprised if the same problem and fix both occur and work for
those machines as well. Something to maybe test later, I suppose.
But for now, anyone got thoughts as to a sane workaround for this?
Perhaps some conditional tweaks in mach-ip32/*.h files somewheres, would
it be simpler to just switch to:
#if defined(CONFIG_64BIT) && (!defined(CONFIG_BUILD_ELF64) ||
defined(CONFIG_SGI_IP32))
(assuming that IP22 doesn't need it; I'll find out later)
"Re-verify range to target, One ping only."
So, anyone got thoughts on this?
I've actually built and booted an SGI IP32 kernel using this logic in
include/asm-mips/page.h, Line 135:
#if defined(CONFIG_64BIT) && (!defined(CONFIG_BUILD_ELF64) ||
(defined(CONFIG_SGI_IP32) || defined(CONFIG_SGI_IP22)))
--Kumba
--
Gentoo/MIPS Team Lead
"Such is oft the course of deeds that move the wheels of the world: small hands
do them because they must, while the eyes of the great are elsewhere." --Elrond
