Re: [SeaBIOS] [PATCH v2] x86emu: Correctly handle 0x66 prefix for some instructions

[Julian Pidancet]

On Thu, Mar 15, 2012 at 10:39 PM, Julian Pidancet
 wrote:
> On Fri, Mar 9, 2012 at 2:08 AM, Guillem Jover  wrote:
> > On Fri, 2012-03-09 at 00:02:55 +0000, Julian Pidancet wrote:
> > > Some instructions are not emulated correctly by x86emu when they
> > > are prefixed by the 0x66 opcode.
> > > I've identified problems in the emulation of these intructions: ret,
> > > enter, leave, iret and some forms of call.
> > >
> > > Most of the time, the problem is that these instructions should push or
> > > pop 32-bit values to/from the stack, instead of 16bit, when they are
> > > prefixed by the 0x66 special opcode.
> > >
> > > The SeaBIOS project aims to produce a complete legacy BIOS
> > > implementation as well as a VGA option ROM, entirely written in C and
> > > using the GCC compiler.
> > >
> > > In 16bit code produced by the GCC compiler, the 0x66 prefix is used
> > > almost everywhere. This patch is necessary to allow the SeaBIOS VGA
> > > option ROM to function with Xorg when using the vesa driver.
> > >
> > > v2: - Decrement BP instead of EBP in accordance with the Intel Manual
> > >     - Assign EIP instead of IP when poping the return address from the
> > >     stack in 32-bit operand size mode in ret_far_IMM, ret_far, and iret
> > >     - When poping EFLAGS from the stack in iret in 32-bit operand size
> > >     mode, apply some mask to preserve Read-only flags.
> > >
> > > Signed-off-by: Julian Pidancet
> >
> > Looks good to me:
> >
> > Reviewed-by: Guillem Jover
> >
> > thanks,
> > guillem
>
> Anyone interested in this ? Is there a maintainer for x86emu ? The
> MAINTAINERS file in xorg-docs doesn't mention anything about it.

CCed: Adam Jackson

Adam, you seem to be the maintainer of the xorg vesa driver. I think
this patch is closely related. Would you mind taking a look at it ?

Thanks,