framebuffer and lilo

[JM Bourdaret <casi@ifrance.com>]

Hello

i can't manage to make the framebuffer of my Riva TNT M64 32M work at boot time:

i have all the settings in hand with fbset, timings and all, all i need is to tell the kernel at boot time.

here is a part of my lilo.conf:
<...>
image=/boot/kern/k245-fb
        label=xrv-fb
#       append="acpi=no-idle hdc=ide-scsi video=riva:800x600"
        append="acpi=no-idle hdc=ide-scsi"
#       append="acpi=no-idle hdc=ide-scsi video=vesa:0x317"
#	the two above works, and the 3 below does not.
#       append="acpi=no-idle hdc=ide-scsi video=vesa:800x600-16"
#       append="acpi=no-idle hdc=ide-scsi video=riva:xres:800,yres:600,pixclock:20023,left:205,right:2,upper:10,lower:0,hslen:100,vslen:15,depth:8"
#       append="acpi=no-idle hdc=ide-scsi video=riva:xres:1024,yres:768,pixclock:12699,left:205,right:32,upper:10,lower:0,hslen:100,vslen:15,depth:8"
        read-only
<...>

the FB is well recognized, i get the cute pingoin and all, 
i can even select the definition with video=riva:800x600 or 1024,
but i need to be more precise, i want to specify the timings and offsets... i got them.

the kernel doesn't recognize the xres:1024,yres:768,pixclock... params, it act just if there were nothing, simple 80x25 screen.

any help or URL would be greatly appreciated. FrameBuffer howto and kernel doc hasn't helped.

jmb