Re: IP32 prom crashes due to __pa() funkiness

[Kumba <kumba@gentoo.org>]

(whoops, reply didn't send to the ML, sorry Frank!)


Franck Bui-Huu wrote:
 > Hi,
 >
[snip]
 >
 > Well, it means that you previously used CONFIG_BUILD_ELF64=y (this
 > implied that PAGE_OFFSET is in XKPHYS) whereas your kernel has CKSEG
 > load address (symbols need PAGE_OFFSET in CKSEG for address
 > translation).
 >
 > So the question is why can't you use CONFIG_BUILD_ELF64=n (and
 > reagarding the current definition of CONFIG_BUILD_ELF64).
 >
[snip]
 >
 > It makes me think that I posted a patch for that a couple of weeks ago:
 >
 > http://marc.theaimsgroup.com/?l=linux-mips&m=117154480225936&w=2
 > http://marc.theaimsgroup.com/?l=linux-mips&m=117154480126802&w=2
 > http://marc.theaimsgroup.com/?l=linux-mips&m=117154587014827&w=2
 >
 > Basically this patch removes CONFIG_BUILD_ELF64 and makes Kbuild to use
 > '-msym32' switch if you really need it. Kbuild makes its choice according
 > the load address of your kernel image.
 >
 > Could you give it a try ? This patch was based on 2.6.20 but it should
 > apply fine on a 2.6.21-rc[12].

Tested, and it still failed.

And I didn't always use CONFIG_BUILD_ELF64.  In fact, for the longest time (up 
until 2.6.17) I built IP32 and 64bit IP22 kernels without CONFIG_BUILD_eLF64, 
passing -mabi=o64 (a.k.a., the binutils hack).  This let me use the plain 
'vmlinux' target w/o the need for an objcopy to boot these systems.  After 
2.6.17, the nature of o64 was mostly neutered, so I switched to using 
CONFIG_BUILD_ELF64 and the 'vmlinux.32' target, as this is apparently the way 
Debian builds their IP32 kernels (and was the way geoman/spbecker said I 
should've been using all along).

So with the changes brought in by __pa(), I suppose a new, RightWay(TM) to build 
IP32 (and conversely, 64bit IP22) kernels needs to be found.  These two systems 
are particularly wacky, hence why they need a bit more special care than more 
traditional, proper, 64bit systems like Origin and Octane.

Also, Peter raises a good point in this case.  It sounds like a re-thinking of 
how all this address stuff is handled will fix not only special cases like 
IP32/IP22, but the really weird systems, like IP28, as well.  Which would be a 
big plus in my opinion.


--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