#1185 BIOS PCI returns with INT flag = 0

[Ben Lunt]

In rombios.c at line 11256

call pcibios_real
jc pcibios_error
retf 2
pcibios_error:

The retf 2 instruction doesn't enable interrupts again like the iret will.

For example, try the following code (as a DOS guest):

       org 100h

       mov  al,'A'
       int  29h

       mov  ah,0B1h    ; INT 1A - PCI BIOS v2.0c+ - FIND PCI CLASS CODE
       mov  al,003h    ;

       mov  ecx,0C0300h ; xxxx_xxxx_0000_1100_0000_0011_0000_0000
                        ; bits 31-24 unused
                        ; bits 23-16 class
                        ; bits 15-8  subclass
                        ; bits 7-0   programming interface

       mov  si,0
       int  1Ah

       mov  al,'B'
       int  29h

       call delay55ms

       mov  al,'C'
       int  29h

       .exit

delay55ms proc near uses es
xor ax,ax
mov es,ax
mov ax,es:[046Ch]
@@: cmp ax,es:[046Ch]
je short @b

       mov  ax,es:[046Ch]

@@: cmp ax,es:[046Ch]
je short @b

       ret

delay55ms endp

Since the bios did not re enable the Interrupts, the BIOS timer tick at 0x0040:006C does not increment.

So, for a fix, would the following work:

call pcibios_real
jc pcibios_error
+ sti
retf 2
pcibios_error:

Or will you have to replace the flags value on the stack with the new flags value, then do a iret as expected?

Thanks,
Ben

[Volker Ruppert]

Fixed in CVS now.