Thanks both ! You were right. The framebuffer support was in the kernel (a debian instalation kernel version 2.2.17-idepci). I didn't think about it.
It's a little bit strange. This kernel has also de configuration lines : CONFIG_FB_VESA=y CONFIG_FB_VGA16=y so support would be quite generic. For the moment I compiled a new kernel without the framebuffer support. Only with de VGA_CONSOLE and VIDEO_SELECT options (they were also selected in the previous kernel...). And it works fine ! May another day I will try with the framebuffer and Permedia 2 support. Thank you very much again ! Unai