doc: remove outdated PCI/RAC/Domain notes
Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
This commit is contained in:
Tiago Vignatti
parent
7b3d05ebd5
commit
d57361bb9a
|
|
@ -1,159 +0,0 @@
|
|||
The purpose of the changes described here is to implement a more general
|
||||
framework for multi-head on systems with more than one host-to-PCI bridge.
|
||||
The changes also implement a basic port of XFree86 to SPARC Solaris.
|
||||
|
||||
These changes are derived from David S. Miller's submission #4653 to the
|
||||
patch list. David Andrew of Sun Microsystems was also kind enough to
|
||||
arrange for a hardware loan for development of these changes.
|
||||
|
||||
These changes are known to work on several SPARC SunOS and UltraSPARC
|
||||
Linux configurations. Linux kernel work is in progress to port these
|
||||
changes to Linux/PowerPC.
|
||||
|
||||
Several loose ends still need to be addressed before these changes can be
|
||||
considered stable. The bulk of this note is devoted to enumerating what
|
||||
remains to be done, along with other notes, broken down into various broad
|
||||
categories.
|
||||
|
||||
SPARC SunOS (aka Solaris)
|
||||
-------------------------
|
||||
- An overview of this XFree86 port is available in README.Solaris.
|
||||
- The keyboard map code in hw/xfree86/os-support/sunos/sun_kbdEv.c needs
|
||||
to be extended to handle more than only the sun5 keyboard I targeted it
|
||||
for. Even for the sun5, the map is incomplete as several keys are not
|
||||
mapped. What is there is just barely usable.
|
||||
- On exit, the server will zero out /dev/fb, but that might not be the
|
||||
right thing to do for all primary adapters. This does however
|
||||
appear to emulate the behaviour of Sun's commercial servers. It also
|
||||
eliminates the need for output drivers to save and restore video memory
|
||||
contents. (They still need to save/restore the mode timing however.)
|
||||
This also chimes into a long-standing XFree86 policy to not save/restore
|
||||
video memory contents if the mode on entry is found to be non-VGA, a
|
||||
policy several existing drivers comply with.
|
||||
- The SBUS drivers (sunbw2, suncg14, suncg3, suncg6, sunffb, sunleo and
|
||||
suntcx), the common layer's SBUS code and the fbdev driver have all
|
||||
only been compile tested. There are likely to be Linux'isms within
|
||||
them that remain to be dealt with.
|
||||
- It still needs to be verified whether or not this work adversely
|
||||
affected support for ix86 Solaris.
|
||||
|
||||
UltraSPARC Linux
|
||||
----------------
|
||||
- Although this code can be compiled using any Linux/SPARC64 kernel, it
|
||||
can only run successfully using 2.4.12 or later.
|
||||
- I haven't had time to sufficiently dig into XKB to properly configure it
|
||||
for sun5 keyboards. Given XFree86 on Linux/SPARC has been around for a
|
||||
while, it's likely someone has already done this, and I'd appreciate
|
||||
receiving a copy of a working XF86Config input section.
|
||||
|
||||
PowerPC Linux
|
||||
-------------
|
||||
- As mentioned above, kernel work is in progress to port this PCI scheme
|
||||
to Linux/PowerPC.
|
||||
- Aside from kernel work, the inX() and outX() definitions in compiler.h
|
||||
will need to be changed to do something akin to their SPARC definitions,
|
||||
i.e. consider their port argument to be a virtual address.
|
||||
|
||||
Other Linux ports to multi-domain architectures
|
||||
-----------------------------------------------
|
||||
- Comments in os-support/bus/linuxPci.c document the kernel interface
|
||||
required to port these changes. In short, Linux ports, such as Alpha
|
||||
and mips, should follow SPARC and PowerPC's lead in providing support to
|
||||
mmap() PCI devices through their /proc/bus/pci pseudo-files and to treat
|
||||
such requests for host bridges as requests to mmap() space provided by
|
||||
these bridges.
|
||||
|
||||
Other OS's
|
||||
----------
|
||||
- In the right hands, either linuxPci.c or sparcPci.c can be used as a
|
||||
guide for what would need to be done to port this scheme to other OS's.
|
||||
Perhaps the largest difference between the two (in terms of interface to
|
||||
the common layer) is that the SunOS port includes internally generated
|
||||
domain numbers in PCITAG's, whereas the Linux port doesn't need to. The
|
||||
remainder of the PCI code (which is OS-independent) can handle either
|
||||
scheme.
|
||||
- Required entry points are xf86GetPciDomain(), xf86MapDomainMemory(),
|
||||
xf86MapDomainIO() and xf86ReadDomainMemory(). Replacements for
|
||||
xf86BusAccWindowsFromOS(), xf86PciBusAccWindowsFromOS() and
|
||||
xf86AccResFromOS() might also be required.
|
||||
- Development of these changes has detected the fact that the XFree86 port
|
||||
to the PowerMax OS is broken, and has been for some time, i.e. since
|
||||
shortly after its introduction, back in the 3.9* days.
|
||||
|
||||
SPARC PCI (OS-independent)
|
||||
--------------------------
|
||||
- The "Simba" PCI-to-PCI bridge used in SPARC's does not implement VGA
|
||||
routing, as defined in the PCI specs. Fortunately, OpenPROM seems to
|
||||
always route VGA resources to the bus with PCI connectors, but this also
|
||||
causes the common layer to not mark any PCI adapter as primary.
|
||||
|
||||
Multiple PCI domains (architecture- and OS-independent)
|
||||
-------------------------------------------------------
|
||||
- This implementation assumes every host-to-PCI bridge provides access to
|
||||
a separate PCI domain. Each such domain provides three different
|
||||
"address" spaces: PCI configuration, I/O and memory. The
|
||||
implementation can also deal with situations where more than one PCI
|
||||
domain share (different subsets of) the same PCI configuration space. I
|
||||
have unconfirmed information that suggests it might be necessary to also
|
||||
allow the sharing of PCI memory spaces.
|
||||
- This implementation also assumes the CPU's physical address space
|
||||
includes the entirety of each domain's I/O and memory spaces. I know
|
||||
this'll need to be changed to deal with the so-called UniNorth bridge,
|
||||
found on PowerPC's, which allows access to only a subset of the memory
|
||||
space behind it.
|
||||
- Ideally, the common layer should mark as primary up to one PCI adapter
|
||||
per domain. This has yet to be done.
|
||||
- Something needs to be done about PCI master aborts on primary buses.
|
||||
For details on this, see my long-winded diatribe in sparcPci.c, and
|
||||
related comments in linuxPci.c. Suffice it to say here that I see the
|
||||
eventual implementation of host bridge drivers within XFree86 as
|
||||
unavoidable at this point.
|
||||
- DGA is broken on multi-domain platforms. The information passed to the
|
||||
client to locate the framebuffer still needs to be revised. The best way
|
||||
to deal with this is to change all drivers' OpenFramebuffer() function to
|
||||
call a common layer routine to set the device name and displacements to be
|
||||
returned to the DGA client.
|
||||
|
||||
Output drivers
|
||||
--------------
|
||||
Most drivers currently used on ix86 need(ed) source code changes.
|
||||
- Calls to xf86ReadBIOS() and xf86MapVidMem() were replaced with calls to
|
||||
xf86ReadDomainMemory() and xf86MapDomainMemory() respectively. Except
|
||||
for the "ati" and "atimisc" modules, this has already been done.
|
||||
- All ix86-style I/O port numbers need to be declared as an IOADDRESS, a
|
||||
type defined in xf86Pci.h as "unsigned long". Such port numbers also
|
||||
need to be offset by a displacement which is also defined as an
|
||||
IOADDRESS. Before a driver's PreInit() is called, the common layer
|
||||
makes this displacement available in ScrnInfoRec.domainIOBase. For
|
||||
single-domain architectures, such as ix86, domainIOBase will always be
|
||||
zero. Current use of vgaHWRec.PIOOffset has also been adjusted
|
||||
accordingly. Some drivers have been changed to keep a copy of this
|
||||
displacement in their private structure. Internally, an IOADDRESS is
|
||||
actually a pointer that has been recasted to an unsigned long, but the
|
||||
common layer "hides" this fact from the driver ABI, which means that I/O
|
||||
port numbers, as seen by drivers, remain as integers rather than
|
||||
addresses. Aside from the ati and atimisc modules, s3, sis and tseng
|
||||
are the only modules left whose I/O still needs to be converted (I've
|
||||
temporarily run out of steam).
|
||||
- Note that these conversions are not necessarily sufficient to produce
|
||||
drivers that will work on any given multi-domain architecture. A driver
|
||||
that, for example, had endianness problems, still does. But, at least,
|
||||
these conversions, along with the supporting common layer changes, make
|
||||
PCI drivers more widely amenable to porting.
|
||||
- rdinx(), wrinx(), modinx(), testrg(), testinx() and testinx2() are not
|
||||
given enough information to allow for the relocation of their I/O. They
|
||||
are consequently being deleted. The apm and ark drivers, the only
|
||||
remaining callers of the first three, have been changed to use local
|
||||
definitions instead. The last three (test*()) were already unused.
|
||||
- As a temporary measure, these changes completely disable ISA-style
|
||||
probing on SPARC's and PowerPC's. This means that driver calls to
|
||||
xf86MatchIsaInstances(), while still valid, will always return detection
|
||||
failure on SPARC's and PowerPC's. This will be dealt with when a more
|
||||
general master abort handling scheme is implemented.
|
||||
- I need to make a decision about the master abort issues mentionned above
|
||||
before I can convert the "ati" and "atimisc" modules. Consequently,
|
||||
these modules still need to be compiled with -DAVOID_CPIO on
|
||||
multi-domain architectures, and support for Mach64 variants as
|
||||
non-primary heads is not yet available.
|
||||
|
||||
$XFree86$
|
||||
Loading…
Reference in New Issue
Block a user