klibc - Jan 2004 - Supporting multiple video cards under Linux

Supporting multiple video cards under Linux

When there are multiple video cards in a machine the system BIOS only
initializes one of them.  So I'm working on a version of the DRI drivers
that
will initialize these non-primary video cards.  The new DRI driver achieves this
via generating a hotplug event that runs a user space program when the driver is
first loaded.

This user space program needs to run very early since you may want to use one of
these cards for your console. Because of this I'm looking at klibc and the
early
boot environment. The reset program works by getting a copy of the card's
VBIOS
and calling it's reset function. To do this the user space app needs to go
into
VM86 mode, or on non-86 architectures run a x86 emulator if need be. You
can't
call the VBIOS from a device driver becuase it has been written assuming that it
will be run in real mode, not protected mode.

I tried linking to klibc but I'm missing some key pieces. I need things like
inb/w/l(), outb/w/l(), iopl(), and vm86 support. Is it possible to get these
added to klibc? These are probably all macros simply generating ASM instructions
or calling the kernel VM86 entry point.


====Jon Smirl
jonsmirl@yahoo.com

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Jon Smirl wrote:
> Supporting multiple video cards under Linux
> 
> When there are multiple video cards in a machine the system BIOS only
> initializes one of them.  So I'm working on a version of the DRI
drivers that
> will initialize these non-primary video cards.  The new DRI driver achieves
this
> via generating a hotplug event that runs a user space program when the
driver is
> first loaded.
> 
> This user space program needs to run very early since you may want to use
one of
> these cards for your console. Because of this I'm looking at klibc and
the early
> boot environment. The reset program works by getting a copy of the
card's VBIOS
> and calling it's reset function. To do this the user space app needs to
go into
> VM86 mode, or on non-86 architectures run a x86 emulator if need be. You
can't
> call the VBIOS from a device driver becuase it has been written assuming
that it
> will be run in real mode, not protected mode.
> 
> I tried linking to klibc but I'm missing some key pieces. I need things
like
> inb/w/l(), outb/w/l(), iopl(), and vm86 support. Is it possible to get
these
> added to klibc? These are probably all macros simply generating ASM
instructions
> or calling the kernel VM86 entry point.
> 
Should be easy enough.  Note that if you require vm86 support, you won't 
be able to port these drivers to x86-64.

	-hpa