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Re: [Qemu-devel] OS/2 Bootloader Some weird behaviour of branch instruct
Re: [Qemu-devel] OS/2 Bootloader Some weird behaviour of branch instruction
Sun, 29 May 2005 17:02:03 +0300
Mozilla/5.0 (OS/2; U; Warp 4.5; en-US; rv:1.0.1) Gecko/20020919 IBM Web Browser for OS/2
J. Mayer wrote:
On Wed, 2005-05-25 at 21:59 +0300, Tero Kaarlela wrote:
I have just realized that when running in LE mode in_asm dump is not
useful because it shows code in BE-format. I'll try to make it print in
LE format. And those invalid opcodes is this because after OS/2 crashes
Qemu tries to start its own code but crashes because before this
Processor should be returned to BE-format?
It should display insns in little-endian format, if you're up to date.
Take a look at the code in disas.c and ppc-dis.c, you'll see the case is
Yes I used out of date binaries(0.6.1 + patches). My mistake sorry.
But the 0x3c opcode is valid ... on POWER2 (namely stfq).
Then I guess you choose a platform which is a RS/6000 with a POWER2, not
I'm afraid POWER1 & POWER2 won't be emuled soon, if they'll ever be...
Please check this point.
Bootloader check PVR at very early stage of boot accepted ones are:
If something else is reported bootloader goes to indefiniteve loop.
I took a look at qemu in_asm & cpu debugging with OS/2 bootloader
under Qemu -prep. And there is something weird happening in my opinion:
This happens after boot.cfg has been gone through and kernel bootstrap
task should start:
0xf0107068: .long 0x10009d81
0xf010706c: tdi 0,r0,27776
0xf0107070: bl F011EDF0 <<= Shouldnt this branch to F011EDF0
instead of going on???
As this is a subroutine call, I guess this routine as already been called from
As Qemu only displays blocks at translation time, you don't have any dump any
when calling a routine twice.
After compiling CVS version lines above look like this:
0xf0107068: lwz r12,16(r29)
0xf010706c: lwz r3,8(r12)
0xf0107070: lwz r11,328(r29)
0xf0107074: cmpwi r11,0
0xf0107078: beq F01070A4
invalid/unsupported opcode: 3c - 16 - 0a (f01072ac) 0x00000300 0
0x00000300: .long 0xf01072ac
invalid/unsupported opcode: 3c - 18 - 1c (f0000730) 0x00000700 0
0x00000700: .long 0xf0000730
Could this be because OS/2 can't handle this much ram(128mb). OS/2 has
always been very specific about maximum memory(ie. versions 1.x can't
boot on machines that report more than 16mb ram. this is one of the
reasons 1.x versions dont boot under Qemu and thats why many BIOSES have
option "boot to OS/2). During 1995 when OS/2 PPC was made 16mb was much
and 32mb was huge amount of memory.