[klibc] Supporting multiple video cards under Linux

Jon Smirl jonsmirl at yahoo.com
Sat Jan 24 15:13:31 PST 2004

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 at yahoo.com

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