this driver makes regions of physical memory accessible as a disk.
to use it, ramdiskinit() has to be called before confinit(), so
that conf.mem[] banks can be reserved. currently, only pc and pc64
kernel use it, but otherwise the implementation is portable.
ramdisks are not zeroed when allocated, so that the contents are
preserved across warm reboots.
to not waste memory, physical segments do not allocate Page structures
or populate the segment pte's anymore. theres also a new SG_CHACHED
attribute.
there isnt much of a point in keep maintaining separate
kernel configurations for terminal and cpu kernels as
the role can be switched with service=cpu boot parameter.
to make stuff cosistent, we will just have one "pc" kernel
and one "pc64" kernel configuration now.
instead of naming devices by ther dynamically assigned device address,
we hash device uniqueue fields from the device descriptor and produce
a 5 digit hex string that will identify the device across machines.
when there is a collision (less than 1% chance with 100 devices),
usbd will append the device address to the name to make it uniqueue
for this machine.
the hname is passed to drivers in the devid argument, which now has
the form addr:hname, where the colon and hname can be omited (for backwards
compatibility).
when the new behaviour isnt desired, nousbhname= environment variable
can be defined giving the old behaviour.
the issues with the previous tsc change where not related to the tsc
but where problems with timesync using an old frequency file. a
patch to fix timesync was commited, so so we reintroduce the *notsc=
again.
we previously used tsc only on cpu kernel. now that
we use it on terminal kernel too, there might be some
surprises ahead.
so make it possible to disable tsc for machines where
the tsc rate is not kept constant across cores or is
dynamically adjusted by power management.
allow the shadow framebuffer (softscreen) to be used with any
vga driver, not just vesa. this removes the ugly scr->paddr = 0
hack employed by vesa driver to force softscreen and adds a
softscreen vgactl message that can switch the feature on and off
at runtime.
softscreen can greatly improve graphics performance when bus
reads are slow even tho it disables hardware acceleration.
