Linux-kernel mailing list archive 1999-41,: Re: bootsect.S changes

# Re: bootsect.S changes

Richard B. Johnson (root@chaos.analogic.com)
Fri, 15 Oct 1999 12:58:15 -0400 (EDT)

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On Fri, 15 Oct 1999, Brian Gerst wrote:

> Richard B. Johnson wrote:
> > I think this is still a 'work in progress'. I hope that somebody adds
> > a directive to gas that tells it to assemble 16-bit code so the source
> > code doesn't have to be wrong to get it to make 16-bit code. The
> > prefix 0x66 is a switch. It changes the default oprand size of the
> > processor. If the processor is in 32-bit mode, 0x66 is used to make
> > it do word, instead of longword operations. If the processor is
> > in 16-bit mode, 0x66 prefix makes it do longword instead of the default
> > word operations. Therefore, an assembler needs to 'know' when to
> > not use 0x66. In other words it needs to know the current operation
> > mode of the processor.
> >
> > Maybe a switch like ".i-32" (Intel 32-bit) ".i-16" (Intel 16-bit)
> > needs to be added to GAS.
> >
>
> It's already there: .code16 and .code32
>

Yep. But with some versions it doesn't work very well:

sc.o(.text+0x7): relocation truncated to fit: R_386_16 data
sc.o(.text+0xc): relocation truncated to fit: R_386_16 data
sc.o(.text+0x10): relocation truncated to fit: R_386_16 data
sc.o(.text+0x15): relocation truncated to fit: R_386_16 data
make: *** [sc] Error 1

You have to turn it on/off depending upon whether you are
accessing data or not. Basically fairly broken.....

Cheers,
Dick Johnson
**** FILE SYSTEM WAS MODIFIED ****
Penguin : Linux version 2.3.13 on an i686 machine (400.59 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.

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