and set VI_WRMAPDIRTY) after we have busied the pages rather than
before. this prevents other threads calling genfs_do_putpages() from
marking the vnode clean again while we're in the process of creating
new writable mappings, since such threads will wait for the page(s) to
become unbusy before proceeding.
fixes the problem recently reported by hannken@ on tech-kern.
Remarks:
1. All processors (x86 or not) for which the vendor has implemented
ACPI I/O access routines are supported. Native instructions are
currently supported only for Intel's "Enhanced Speedstep". Code for
"PowerNow!" (AMD) will be merged later. Native support for VIA's
"PowerSaver" will be investigated.
2. Backwards compatibility with existing userland code is maintained.
Comparable to the case with cpu_idle(9), the ACPI CPU driver
installs alternative functions for the existing sysctl(8) controls.
The "native" behavior (if any) is restored upon detachment.
3. The dynamic nature of ACPI-provided P-states needs more investigation.
The maximum frequency induced (but not forced) by the firmware may
change dynamically. Currently, the sysctl(8) controls error out with
a value larger than the dynamic maximum. The code itself does not
however yet react to the notifications from the firmware by changing
the frequencies in-place. Presumably the system administrator should
be able to choose whether to use dynamic or static frequencies.
write-through map (i.e. map it without BUS_DMA_COHERENT) since
currently all DMA data transfers are memory to device only.
Disabled by default, but enabled by "options PXA2X0_LCD_WRITETHROUGH"
or setting pxa2x0_lcd_writethrough = 1 in a kernel binary.
Tested on WS003SH by me and on WS011SH by jun@, and console output speed
is improved ~three times faster than coherent (uncached) mapping.
XXX: should we have a flag like BUS_DMA_WRITETHROUGH in MI bus_dma(9)?
model value.
Required to avoid faulting on rdmsr(MSR_FSB_FREQ) early during boot.
Will ask for a pull-up. This affects GENERIC, and most likely, install iso
too.
XXX quick hack. Obtaining FSB through ACPI should be cleaner.
to type 'make obj' and have it work from any directory, and if you
try from /usr/src/compat, this does not work because the build does
not automatically add -m $topdir/share/mk in that case.
