[ros-dev] [ros-diffs] [dgorbachev] 42305: Add a hack in KiSystemStartupReal function until Better Times.

[Aleksey Bragin]

That function is not supposed to be called by old bootloader  
directly. Why is that needed? And why in this function?


WBR,
Aleksey Bragin.

On Jul 30, 2009, at 9:54 PM, dgorbachev at svn.reactos.org wrote:

> Author: dgorbachev
> Date: Thu Jul 30 19:54:01 2009
> New Revision: 42305
>
> URL: http://svn.reactos.org/svn/reactos?rev=42305&view=rev
> Log:
> Add a hack in KiSystemStartupReal function until Better Times.
>
> Modified:
>     trunk/reactos/ntoskrnl/ke/i386/kiinit.c
>
> Modified: trunk/reactos/ntoskrnl/ke/i386/kiinit.c
> URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ke/ 
> i386/kiinit.c?rev=42305&r1=42304&r2=42305&view=diff
> ====================================================================== 
> ========
> --- trunk/reactos/ntoskrnl/ke/i386/kiinit.c [iso-8859-1] (original)
> +++ trunk/reactos/ntoskrnl/ke/i386/kiinit.c [iso-8859-1] Thu Jul 30  
> 19:54:01 2009
> @@ -712,18 +712,34 @@
>      Ke386SetDs(KGDT_R3_DATA | RPL_MASK);
>      Ke386SetEs(KGDT_R3_DATA | RPL_MASK);
>
> -    /* Save NMI and double fault traps */
> -    RtlCopyMemory(&NmiEntry, &Idt[2], sizeof(KIDTENTRY));
> -    RtlCopyMemory(&DoubleFaultEntry, &Idt[8], sizeof(KIDTENTRY));
> -
> -    /* Copy kernel's trap handlers */
> -    RtlCopyMemory(Idt,
> -                  (PVOID)KiIdtDescriptor.Base,
> -                  KiIdtDescriptor.Limit + 1);
> -
> -    /* Restore NMI and double fault */
> -    RtlCopyMemory(&Idt[2], &NmiEntry, sizeof(KIDTENTRY));
> -    RtlCopyMemory(&Idt[8], &DoubleFaultEntry, sizeof(KIDTENTRY));
> +    /* HACK compensates for KiRosPrepareForSystemStartup hack */
> +    if ((ULONG)Idt == KiIdtDescriptor.Base)
> +    {
> +        USHORT FlippedSelector;
> +
> +        FlippedSelector = KiIdt[2].Selector;
> +        KiIdt[2].Selector = KiIdt[2].ExtendedOffset;
> +        KiIdt[2].ExtendedOffset = FlippedSelector;
> +
> +        FlippedSelector = KiIdt[8].Selector;
> +        KiIdt[8].Selector = KiIdt[8].ExtendedOffset;
> +        KiIdt[8].ExtendedOffset = FlippedSelector;
> +    }
> +    else
> +    {
> +        /* Save NMI and double fault traps */
> +        RtlCopyMemory(&NmiEntry, &Idt[2], sizeof(KIDTENTRY));
> +        RtlCopyMemory(&DoubleFaultEntry, &Idt[8], sizeof(KIDTENTRY));
> +
> +        /* Copy kernel's trap handlers */
> +        RtlCopyMemory(Idt,
> +                      (PVOID)KiIdtDescriptor.Base,
> +                      KiIdtDescriptor.Limit + 1);
> +
> +        /* Restore NMI and double fault */
> +        RtlCopyMemory(&Idt[2], &NmiEntry, sizeof(KIDTENTRY));
> +        RtlCopyMemory(&Idt[8], &DoubleFaultEntry, sizeof(KIDTENTRY));
> +    }
>
>  AppCpuInit:
>      /* Loop until we can release the freeze lock */
>
>