Attached is a patch to SheepShaver to fix memory allocation problems when OS X 10.5 is the host. It also relaxes the 512 MB RAM limit on OS X hosts.
Problem
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Some users have been unable to run SheepShaver on OS X 10.5 (Leopard) hosts. The symptom is error "ERROR: Cannot map RAM: File already exists".
SheepShaver allocates RAM at fixed addresses. If it is running in "Real" addressing mode, and can't allocate at address 0, then it was hard-coded to allocate the RAM area at 0x20000000. The ROM area as allocated at 0x40800000.
The normal configuration is for SheepShaver to run under SDL, which is a Cocoa wrapper. By the time SheepShaver does its memory allocations, the Cocoa application has already started. The result is the SheepShaver memory address space already contains libraries, fonts, Input Managers, and IOKit areas.
On Leopard hosts these areas can land on the same addresses SheepShaver needs, so SheepShaver's memory allocation fails.
Solution
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The approach is to change SheepShaver (on Unix & OS X hosts) to allocate the RAM area anywhere it can find the space, rather than at a fixed address.
This could result in the RAM allocated higher than the ROM area, which causes a crash. To prevent this from occurring, the RAM and ROM areas are allocated contiguously.
Previously the ROM starting address was a constant ROM_BASE, which was used throughout the source files. The ROM start address is now a variable ROMBase. ROMBase is allocated and set by main_*.cpp just like RAMBase.
A side-effect of this change is that it lifts the 512 MB RAM limit for OS X hosts. The limit was because the fixed RAM and ROM addresses were such that the RAM could only be 512 MB before it overlapped the ROM area.
Impact
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The change to make ROMBase a variable is throughout all hosts & addressing modes.
The RAM and ROM areas will only shift when run on Unix & OS X hosts, otherwise the same fixed allocation address is used as before.
This change is limited to "Real" addressing mode. Unlike Basilisk II, SheepShaver *pre-calculates* the offset for "Direct" addressing mode; the offset is compiled into the program. If the RAM address were allowed to shift, it could result in the RAM area wrapping around address 0.
Changes to main_unix.cpp
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1. Real addressing mode no longer defines a RAM_BASE constant.
2. The base address of the Mac ROM (ROMBase) is defined and exported by this program.
3. Memory management helper vm_mac_acquire is renamed to vm_mac_acquire_fixed. Added a new memory management helper vm_mac_acquire, which allocates memory at any address.
4. Changed and rearranged the allocation of RAM and ROM areas.
Before it worked like this:
- Allocate ROM area
- If can, attempt to allocate RAM at address zero
- If RAM not allocated at 0, allocate at fixed address
We still want to try allocating the RAM at zero, and if using DIRECT addressing we're still going to use the fixed addresses. So we don't know where the ROM should be until after we do the RAM. The new logic is:
- If can, attempt to allocate RAM at address zero
- If RAM not allocated at 0
if REAL addressing
allocate RAM and ROM together. The ROM address is aligned to a 1 MB boundary
else (direct addressing)
allocate RAM at fixed address
- If ROM hasn't been allocated yet, allocate at fixed address
5. Calculate ROMBase and ROMBaseHost based on where the ROM was loaded.
6. There is a crash if the RAM is allocated too high. To try and catch this, check if it was allocated higher than the kernel data address.
7. Change subsequent code from using constant ROM_BASE to variable ROMBase.
Changes to Other Programs
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emul_op.cpp, main.cpp, name_registery.cpp, rom_patches.cpp, rsrc_patches.cpp, emul_ppc.cpp, sheepshaver_glue.cpp, ppc-translate-cpp:
Change from constant ROM_BASE to variable ROMBase.
ppc_asm.S: It was setting register to a hard-coded literal address: 0x40b0d000. Changed to set it to ROMBase + 0x30d000.
ppc_asm.tmpl: It defined a macro ASM_LO16 but it assumed that the macro would always be used with operands that included a register specification. This is not true. Moved the register specification from the macro to the macro invocations.
main_beos.cpp, main_windows.cpp: Since the subprograms are all expecting a variable ROMBase, all the main_*.cpp pgrams have to define and export it. The ROM_BASE constant is moved here for consistency. The mains for beos and windows just allocate the ROM at the same fixed address as before, set ROMBaseHost and ROMBase to that address, and then use ROMBase for the subsequent code.
cpu_emulation.h: removed ROM_BASE constant. This value is moved to the main_*.cpp modules, to be consistent with RAM_BASE.
user_strings_unix.cpp, user_strings_unix.h: Added new error messages related to errors that occur when the RAM and ROM are allocated anywhere.
This first patch gets B2 and SS to build under Leopard and Tiger.
I tested this on a 32-bit intel 10.5.6 mac like so:
B2
./autogen.sh --disable-standalone-gui --enable-vosf --enable-sdl-video --enable-sdl-audio --enable-addressing=real --without-esd --without-gtk --without-mon --without-x
SS
./autogen.sh --disable-standalone-gui --enable-vosf -enable-sdl-video --disable-sdl-audio --enable-addressing=real --without-esd --without-gtk --without-mon --without-x --enable-jit
There is also a little tweak so that you can use sdl audio in SheepShaver when building for Mac OS X.
clicks to right-clicks and option-clicks to middle-clicks, a feature intended
for Mac users with single-button mice who are running SDL-based games that
require a multi-button mouse. This is unhelpful in SheepShaver, where we want
command-clicks and option-clicks to be passed through unchanged to the emulated
Mac OS. We can disable the unwanted behavior by setting an environment variable
SDL_HAS3BUTTONMOUSE intended for this very purpose.
A similar change in main_windows.cpp is NOT required, because only the Quartz
video implementation is involved.
By SDL convention, putenv is used in preference to setenv, although for Unix
platforms it doesn't matter.
SheepShaver since we are typically translating SDL_QUIT events to PowerOff()
on MacOS side. And, if MacOS is not fully booted, it's not really convenient
to shut it down, even with ctrl-C. i.e. you had to kill -9 it.
1 GB of Mac memory. Only tested on Linux/x86_64 so far but with a somewhat
interesting (MacOS, ROM, RAM size) matrix.
XXX: It should be possible to allocate up to 1.5 GB by relocating the ROM
base to something like 0x60800000.
Others changes include:
- Factor out STR_SIG_INSTALL_ERR messages
- Process command line arguments early (prior to calling PrefsInit())
- GUI: set start_clicked only if the "Start" button was clicked
- GUI: save changes to the "Input" pane when the "Start" button was clicked
(idle_wait) until events arrived and notified through TriggerInterrupt().
i.e. we no longer sleep a fixed amount of time on platforms that support
a thread wait/signal mechanism.
i.e. it returned EPERM and ran into stack corruption to eventually crash the
emulator. This is noticeable in !hw_mac_cursor_accl mode (e.g. fullscreen DGA).
In order to the sigalstack() to be effective, we must kludge the kernel to
think it's running on another stack. In practise, we provide another stack
for the SIGUSR2 handler. sigusr2_handler_init() fulfills that purpose.
I hope this fixes remaining issues forever. At some point, I had multiple
*_init() handlers in case this is necessary.
for systems that use a global r2 as the TLS register, e.g. Linux/ppc with
newer glibc. Also remove the syscall junk which were simply workarounds
for this bug. Remove a duplicate r2 restoration in EmulOp.
BTW, it's possible to get SheepShaver running on Linux/ppc systems with
NPTL rather than SheepThreads.
to /dev/mem is required on Linux to use XF86 DGA mode. Otherwise, there is
now a fallback to fbdev.
- Forward port some features from Basilisk II (set_window_name,
disable_mouse_accel).
- Don't SIGSTOP the emulation thread on suspend since that would completely
stop the process on Linux. Use a frame buffer lock instead (as B2 does)
in that case. Tell me if I broke other arches, e.g. r13 is no longer saved
in Video and Ethernet stubs, though it seems to be OK.
Colateral feature: SheepShaver should now run on Linux/ppc64 with relevant
32-bit runtime. Native Linux/ppc64 support is harder as low mem globals are
32-bit in mind and e.g. the TLS register there is %r13, %r2 is the TOC
(PowerOpen/AIX ABI)
a read-only page, it can also be used to detect overlaps between Procedure
space and Data space.
Provide native Windows implementation of shared MacOS KernelData allocation.
This is moved under main() so that to avoid a weird linking error. This native
implementation is independent of Cygwin IPC (and possible background server)
code was also trying to access Serial memory.
Note however that I noticed some rare crashes with the DR emulator.
Probably caused by nested runs from EmulOps? We'd really want a native
68k emulator too for Execute68k() things.
