From: nowhere@never.at   
      
   On 25/03/2023 13:32, muta...@gmail.com wrote:   
   ...   
   > Ok, it's still unclear to me what (artificial) constraints   
   > you are placing, and why, but they are clearly genuine   
   > constraints, and that is an interesting use case scenario.   
      
   it's easy to explain: I hate folks who sell unfinished stuff.   
   M$ is the worst on this matter.   
   So I spent as less money as possible for windoze,   
   I once bought DOS3.11 and later win98SE, I found copies of XP and win7   
   and  finally I was forced to buy a win10 (I really hate it).   
   But OTOH it was this stupid M$-stuff which made me create my own OS.   
      
   >>>> So you can do this tests and report what you found.   
   >>> If you give me a specific instruction to test (ie something   
   >>> that will assemble with the mingw assembler), I can do so.   
      
   >> dunno mingw, but it may be able to use "db HEX" like other ASM do.   
      
   > I don't know how to do that. Rather than try to find out,   
   > I simply tried the mnemonics.   
      
   >> 33 C9 XOR ecx,ecx   
   >> B1 1B MOV CL.0x1B ;make RCXX==0x1B (returns APIC_BASE on AMDs)   
   >> 0F 32 RDMSR ;may crash if this MSR doesn't exist or CPL>0   
      
   >> or an easier one:   
   >> 0F 09 WBINV ;alters no registers crash if CPL>0.   
   > I started with the easier one, but it didn't assemble.   
   > But this one assembled:   
   > .globl efimain   
   > efimain:   
   >   
   > # wbinv   
   >   
   > xor ecx,ecx   
   > mov cl, 0x1b   
   > rdmsr   
   >   
   > xxx: jmp xxx   
   > #ret   
      
   Now you know that the boot code runs in PL0 ?   
   :):):) LMFAO it would otherwise not make much sense!   
   ...   
   >> haven't found anything mentioned about start condition in these docs so   
   >> far.   
   > Ok. So reverse-engineering turned out to be easier.   
      
   and sometimes logical thinking helps too :)   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)