- Added an overloaded version of attach_pci_device which takes a suffix string that can be used to make a device name unique so that multiple devices of the same class can be added to a machine. The method returns a PCIDevice which can be easily used to attach more PCI devices if it is a PCIHost.
PCIDevice
- supports_io_space method now uses a flag has_io_space which is automatically set for PCI bridges or PCI devices that have an I/O BAR.
atirage
- Devices that have I/O BARs don't need a supports_io_space method.
mpc106
- Devices that don't have I/O methods don't need a supports_io_space method.
A multi-function device may have functions of the same class (e.g. a USB device with two OHCI functions) but each function should be initialized with a different interrupt pin.
Add PCI bridge and multi-function device support.
Overview:
- A multi-function device is two or more PCIDevices with the same device number but one device is function zero (as with currently implemented PCIDevices) and the other functions have function numbers between 1 and 7. The device number and function number are properties of the PCIDevice's parent PCIHost connection.
- A PCIBridge is a PCIHost (it can connect child PCI devices) and a PCIDevice (it has config space, BARs, and expansion ROM).
- A PCIDevice has Type 0 header. It has 6 BARs.
- A PCIBridge has Type 1 header. It has 2 BARs. The config space registers beginning from offset 0x18 differ from those of a PCIDevice.
Possible future modifications:
- Add a PCICardBus class. It is a PCIHost. It has Type 2 header. It has one BAR. The first 20 bytes match Type 0 and Type 1 headers. These exist in New World Macs. They allow hot-plug of PCI devices.
- Split base PCI registers (first 16 bytes) into a PCIBase class. Type 1 and 2 have two or one BAR but I think all 6 BARs belong in PCIBase class anyway.
- Split PCIHost into two classes: Currently existing PCIHosts (Bandit, Grackle) are PCIHost and PCIRoot (they have the broadcast I/O requests functionality) while PCIBridge is PCIHost only - it can propagate I/O requests but does not originate the broadcast.
- pci_register_mmio_region should maybe return a pointer to a region struct so that it can be used for unregistering or modifying the region's range. This may be useful for PCI bridges which have ranges that may constrain memory BARs of their downstream devices.
PCIDevice
- Moved expansion ROM BAR handling to a separate function pci_wr_exp_rom_bar so that it can be used by both PCI devices and PCI bridges which have the ROM BAR in different locations. It now supports unmapping expansion ROM. Also made exp_rom_bar not writable if there's no ROM.
- Added num_bars field which specifies the number of valid BARs since Type 0, 1, and 2 headers have different number of BARs.
- map_exp_rom_mem now properly unmaps expansion ROM (using new function unmap_exp_rom_mem) before mapping it again.
- Added function set_multi_function which modifies hdr_type to indicate if a device has other functions. This is to be applied only to devices with function number 0.
PCIHost
- When attaching a PCI device, it will check if it's a multi-function device (there exists an attached function that is not zero) and adjust hdr_type of function 0 of the device accordingly.
- Attached PCI bridges are added to a list of PCI bridges attached to the host.
- Added pci_io_read_loop and pci_io_write_loop which loop through attached PCI devices to find one that will perform the action for the given I/O address without logging an error (since some other device might perform the action).
- Added pci_io_read_broadcast and pci_io_write_broadcast which are used by a PCI root (bandit/grackle). They will log an error if the action is not performed. They should probably do a machine check exception to match real Power Macs.
- pci_find_device (used by PCI root) will recursively find a PCIDevice for type 1 config register accesses.
- Logging from PCIHost now includes the name of the PCIHost instead of just "PCIHost" because there can be multiple PCI hosts.
PCIBridge
- Sets num_bars to 2 and hdr_type to 1.
- I/O ranges set in the config registers are handled correctly by pci_io_read and pci_io_write.
- Memory ranges set in the config registers do not currently affect memory mmio regions. It is assumed that Open Firmware and the OS will set the ranges and BARs correctly to allow all BARs to be accessed fully.
bandit, mpc106
- Bandit and Grackle now call pci_io_read_broadcast and pci_io_read_broadcast to pass I/O accesses to downstream PCI devices.
- Chaos is modified to work like Bandit even though it will never have PCI bridges attached or devices that support I/O accesses. It's simpler this way.
PCIHost
- PCIHosts (bandit and grackle) now use device number and function number for identifying attached PCIDevices. A macro DEV_FUN is added to calculate this new slot_id. Bandit no longer uses IDSEL. Grackle no longer uses only device number.
machinecatalyst, machinegossamer, machinetnt
- Use DEV_FUN to attach PCI devices by device number and function number.
- Don't log anything if the I/O access is not for this device. A different device might handle it.
- Don't return true for I/O access if an I/O access is not performed. Otherwise the I/O access won't be passed to other devices.
While dingusppc only emulates 32-bit Macs (for now), it is possible for a 32-bit Power Mac to use a PCIe card that has 64-bit BARs.
finish_config_bars is added to scan the cfg values of the BARs and determine their type. The type is stored separately so that it does not need to be determined again.
The type can be I/O (16 or 32 bit) or Mem (20 or 32 or 64 bit). A 64 bit bar is two BARs, the second contains the most significant 32 bits.
set_bar_value uses the stored type instead of trying to determine the type itself. It is always called even when the firmware is doing sizing. For sizing, It does the job of setting the bar value so do_bar_sizing is now just a stub.
Every PCIDevice that has a BAR needs to call finish_config_bars after setting up the cfg values just as they need to setup the cfg values. Since they need to do both, maybe the cfg values should be arguments of finish_config_bars, then finish_config_bars() should be renamed config_bars().
- Macros need parenthesis to enforce operation order when expanded.
- Fix device and register numbers in log messages.
- Unmapped I/O space reads don't necessarily return 0xffffffff. That's only for config space reads. Just return 0. Unhandled I/O space read should probably cause a memory check (TEA - Transfer Error Acknowledge) exception as it does on a Power Mac 8600.
dingusppc could not read bytes from offset 1,2,3 or words from offset 2.
dingusppc did not read words from offset 1,3 and longs from offset 1,2,3 in the same way as a real Power Mac 8600 or B&W G3.
This commit fixes those issues.
- Added pci_cfg_rev_read. It takes a 32 bit value from offset 0 and returns a value of the specified size using bytes starting from the specified offset. Offsets 4,5, & 6 wrap around to 0,1, & 2 respectively. The result bytes are in flipped order as required by the read method (so a value of 0x12345678 is returned as 0x78563412)
A real Power Mac 8600 might return a random byte for offset 4, 5, 6 for vci0 but usually not for pci1. A B&W G3 seems to always wrap around correctly. We won't read random bytes, and we won't read a default such as 00 or FF. We'll do the wrap around which makes the most sense because writing 0x12345678 to any offset and reading from the same offset should produce the value that was written.
- Added pci_cfg_rev_write. It takes a 32 bit value from offset 0, and modifies a specified number of bytes starting at a specified offset with the offset wrapping around to 0 if it exceeds 3. The modified bytes take their new values from the flipped bytes passed to pci_cfg_write. When size is 4, the original value is not used since all bytes will be modified.
Basically, those two functions handle all the sizes and all the offsets and replace calls to BYTESWAP_32, read_mem or read_mem_rev, and write_mem or write_mem_rev.
read_mem_rev, as it was used by pcidevice and some other places, could read beyond offset 3 if it were ever passed a reg_offs value that did not have offset as 0. Since the offset was always zero, it would always read the wrong byte or word if they were not at offset 0. Same for read_mem as used by mpc106.
write_mem_rev, as it was used by pcidevice and some other places, could write beyond offset 3 if it were ever passed a reg_offs value that did not have offset as 0. Since the offset was always zero, it would always write the wrong byte or word if they were not at offset 0. Same for write_mem as used by mpc106.
pcidevice:
- The logging macros should be used to handle all config register access logging.
- Unaligned PCI config register accesses will be output as ERROR instead of WARNING.
- The logging macros include the offset and size. They also include the value for named registers or for writes.
- Added MMIODevice read and write methods so that PCIDevice is not abstract if a PCIDevice doesn't override the read and write method since some PCIDevices don't have MMIO.
pcihost:
- Added pci_find_device stub for handling PCI bridges in future commit.
bandit and mpc106:
- PCI host controllers will handle all PCI config access alignment and sizing. A PCIDevice will always access config registers as 32 bits on a 4 byte boundary. The AccessDetails passed to a PCIDevice config read or write method is there only for logging purposes.
bandit:
- Common MMIO code is moved to new BanditHost class so both Bandit and Chaos can use it. PCI related code is moved to new BanditPCI class.
- Simplify IDSEL to/from PCI device number conversion by removing the shift or subtract.
- Remove BANDIT_ID_SEL check. The IDSEL conversion to PCI device number can find the bandit PCI device.
- For logging, make best guess of PCI device number from invalid IDSEL - the result is always reasonable for device 0x00 to 0x0A when accessing config register 0x00 (as one would do when scanning for PCI devices like lspci does).
mpc106:
- Common config space code is put in cfg_setup. It handles extracting the offset.
- Added code to log access to unimplemented config registers of grackle.
- Don't call setup_ram when writing to config registers that setup_ram doesn't use.
- pci_cfg_read calls READ_DWORD_LE_A and pci_cfg_write calls WRITE_DWORD_LE_A. When reading or writing memory that is organized as little endian dwords, such as my_pci_cfg_hdr of mpc106, the function should explicitly state that it's little endian so that the emulator may be ported one day to a CPU architecture that is not little endian.
atirage:
- The changes correctly place user_cfg at byte 0x40 instead of 0x43 and writes the correct byte depending on size and offset.
Use explicit cast when converting large integer types to smaller integer types when it is known that the most significant bytes are not required.
For pcidevice, check the ROM file size before casting to int. We'll allow expansion ROM sizes up to 4MB but usually they are 64K, sometimes 128K, rarely 256K.
for machinefactory, change the type to size_t so that it can correctly get the size of files that are larger than 4GB; it already checks the file size is 4MB before we need to cast to uint32_t.
For floppyimg, check the image size before casting to int. For raw images, only allow files up to 2MB. For DiskCopy42 images, it already checks the file size, so do the cast after that.
It might not be an error - usually it just means that it was already allocated so demote this message to a warning.
Related memory allocation changes:
- Added find_range_exact which searches for an allocation that exactly matches a range.
- Added find_range_contains which searches for an allocation that is completely contained within a range.
- Added find_range_overlaps which searches for an allocation that overlaps any part of a range.
- Added is_range_free which is similar to the above three. It returns false if any allocated range overlaps a range. It reports the regions that it overlaps.
- Fix add_mem_region and add_memio_region so that they don't just check the first byte and last byte.
- Memory allocation logging should include the range (first byte..last byte) and device if possible.
- Log memory allocations.
First, remove name override for subclasses of HWComponent (Chaos and ScsiBus) because HWComponent has its own name field.
HWComponent name should be set as early as possible in the constructor so it can be used in log messages.
PCIDevice should set name of HWComponent (through MMIODevice) in its constructor, using the name that is given to its constructor.
For Bandit and Grackle, they don't need to set the HWComponent name since its PCIDevice constructor will now do it.
Chaos is not a PCIDevice so it should set the MMIODevice name itself.
Why does PCIDevice have a name that is separate from the HWComponent name?
BAR 0 exists on a real Power Mac 8600 and the dingusppc 7500.
On a Power Mac 8600, the initial value is 0x84000003. In Open Firmware, you can write to all bits of the BAR and read the value back except the 2 least significant bits are always %11. Bit 0 indicates I/O space. Bit 1 is reserved and should be zero so maybe this is not a real I/O space BAR. 0x8400000 is written to the BAR by Open Firmware. It doesn't look like a normal I/O address which are usually 16 bits.
On the emulated 7500, 0x02000000 is written to the BAR by Open Firmware sometime during probe-all. The BAR did not behave as it does in the Power Mac 8600. This commit fixes that.
Two questions remain:
1) Which fcode writes to the BAR? Is it the probe fcode or is it the control fcode? There's no config-_! in the control fcode.
2) What is the purpose of the BAR? Writing to it can cause a hang. The testbits code below seems to succeed - it restores the original value after reading the result of testing each bit and before displaying the result. The values shown for the MSB (0x84 on the 8600 and 0x02 on the 7500) could be three flag bits.
```
dev vci0
: testbits { adr ; org }
cr
adr config-l@ dup -> org ." original : " 8 u.r cr
20 0 do
1 1f i - << dup 8 u.r ." : "
adr config-l!
adr config-l@
org adr config-l!
8 u.r cr
loop
;
15810 testbits \ 15810 is the address of the BAR on the emulated 7500.
```
Usually bit 1 of I/O BARs is 0 since it is reserved, but control has an I/O BAR where this bit is set.
bar_cfg is used to determine the default values of the least significant bits (2 bits for I/O BARs and 4 bits for Memory BARs).
The upper bits of bar_cfg determine which bits can be set and also determines the size of the BAR.
Writes to config registers of invalid or non-existent PCI devices are logged. They should be logged with most significant byte first.
The values enter the methods in reverse byte order so they need to be byte swapped (except when size is 1) for logging.
The result is that this command in Open Firmware:
`12345678 16800 config-l!`
will log this:
`VCI0 err: write attempt to non-existing VCI device ??:0d.0 @00.l = 12345678`
The bits that can be set are the enable bit (bit 0) plus the bits represented by exp_bar_cfg which is determined by the size of the ROM which is calculated to be a power of 2 and a minimum of 2K.
The Pointer to PCI Data Structure is supposed to be two bytes. It is described in the PCI Firmware Specification Revision 3.0, section 5.1.1. PCI Expansion ROM Header Format.
The pointer is two bytes at 0x18. The pointer is supposed to be a multiple of 4 which means there's always at least two bytes of padding after the pointer. Some BIOS firmware images may use the 2 bytes following the pointer for other purposes (plus additional bytes before the PCI Data Structure) so we cannot assume the bytes will be zero.
Some PCI expansion ROMs may include both BIOS and Open Firmware images.
dingusppc could not read bytes from offset 1,2,3 or words from offset 2.
dingusppc did not read words from offset 1,3 and longs from offset 1,2,3 in the same way as a real Power Mac 8600 or B&W G3.
This commit fixes those issues.
- Added pci_cfg_rev_read. It takes a 32 bit value from offset 0 and returns a value of the specified size using bytes starting from the specified offset. Offsets 4,5, & 6 wrap around to 0,1, & 2 respectively. The result bytes are in flipped order as required by the pci_cfg_read method (so a value of 0x12345678 is returned as 0x78563412)
A real Power Mac 8600 might return a random byte for offset 4, 5, 6 for vci0 but usually not for pci1. A B&W G3 seems to always wrap around correctly. We won't read random bytes, and we won't read a default such as 00 or FF. We'll do the wrap around which makes the most sense because writing 0x12345678 to any offset and reading from the same offset should produce the value that was written.
- Added pci_cfg_rev_write. It takes a 32 bit value from offset 0, and modifies a specified number of bytes starting at a specified offset with the offset wrapping around to 0 if it exceeds 3. The modified bytes take their new values from the flipped bytes passed to pci_cfg_write. When size is 4, the original value is not used since all bytes will be modified.
Basically, those two functions handle all the sizes and all the offsets and replace calls to BYTESWAP_32, read_mem or read_mem_rev, and write_mem or write_mem_rev.
read_mem_rev, as it was used by pcidevice and some other places, could read beyond offset 3 if it were ever passed a reg_offs value that did not have offset as 0. Since the offset was always zero, it would always read the wrong byte or word if they were not at offset 0. Same for read_mem as used by mpc106.
write_mem_rev, as it was used by pcidevice and some other places, could write beyond offset 3 if it were ever passed a reg_offs value that did not have offset as 0. Since the offset was always zero, it would always write the wrong byte or word if they were not at offset 0. Same for write_mem as used by mpc106.
The PCI controllers (bandit, chaos, mpc106) need to encode the offset (0,1,2,3) into the reg_offs parameter passed to pci_cfg_read and pci_cfg_write so they can return or modify the correct bytes of the dword at reg_offs & 3.
The pci_cfg_read and pci_cfg_write methods extract the offset from reg_offs and report unaligned accesses.
pci_cfg_read uses pci_cfg_rev_read to read from the reg using the size and offset to determine which bytes to read.
pci_cfg_write uses pci_cfg_rev_write to write to the reg using the size and offset to determine which bytes to modify.
Other changes:
- for unimplemented config register reads and writes, bandit and ATIRage now includes offset and size (and value in the case of writes) in log warnings.
- for unimplemented config register reads and writes, pcidevice now includes offset in log warnings.
- pci_read and pci_write of mpc106 require an offset parameter since config_addr does not contain the offset (it is always a multiple of 4). The offset is included in the log warninings for non-existent PCI devices.
- ATIRage uses pci_cfg_rev_read and pci_cfg_rev_write which correctly places user_cfg at byte 0x40 instead of 0x43 and writes the correct byte depending on size and offset.
Notes:
- pci_cfg_read calls READ_DWORD_LE_A and pci_cfg_write calls WRITE_DWORD_LE_A. When reading or writing memory that is organized as little endian dwords, such as my_pci_cfg_hdr of mpc106, the function should explicitly state that it's little endian so that the emulator may be ported one day to a CPU architecture that is not little endian.
Writes to config registers of invalid or non-existent PCI devices are logged. They should be logged with most significant byte first.
The values enter the methods in reverse byte order so they need to be byte swapped (except when size is 1) for logging.
The result is that this command in Open Firmware:
`12345678 16800 config-l!`
will log this:
`VCI0 err: write attempt to non-existing VCI device ??:0d.0 @00.l = 12345678`
BAR 0 exists on a real Power Mac 8600 and the dingusppc 7500.
On a Power Mac 8600, the initial value is 0x84000003. In Open Firmware, you can write to all bits of the BAR and read the value back except the 2 least significant bits are always %11. Bit 0 indicates I/O space. Bit 1 is reserved and should be zero so maybe this is not a real I/O space BAR. 0x8400000 is written to the BAR by Open Firmware. It doesn't look like a normal I/O address which are usually 16 bits.
On the emulated 7500, 0x02000000 is written to the BAR by Open Firmware sometime during probe-all. The BAR did not behave as it does in the Power Mac 8600. This commit fixes that.
Two questions remain:
1) Which fcode writes to the BAR? Is it the probe fcode or is it the control fcode? There's no config-_! in the control fcode.
2) What is the purpose of the BAR? Writing to it can cause a hang. The testbits code below seems to succeed - it restores the original value after reading the result of testing each bit and before displaying the result. The values shown for the MSB (0x84 on the 8600 and 0x02 on the 7500) could be three flag bits.
```
dev vci0
: testbits { adr ; org }
cr
adr config-l@ dup -> org ." original : " 8 u.r cr
20 0 do
1 1f i - << dup 8 u.r ." : "
adr config-l!
adr config-l@
org adr config-l!
8 u.r cr
loop
;
15810 testbits \ 15810 is the address of the BAR on the emulated 7500.
```
Usually bit 1 of I/O BARs is 0 since it is reserved, but control has an I/O BAR where this bit is set.
bar_cfg is used to determine the default values of the least significant bits (2 bits for I/O BARs and 4 bits for Memory BARs).
The upper bits of bar_cfg determine which bits can be set and also determines the size of the BAR.
The bits that can be set are the enable bit (bit 0) plus the bits represented by exp_bar_cfg which is determined by the size of the ROM which is calculated to be a power of 2 and a minimum of 2K.
PCI config read fails should return all 1 bits.
All unused registers in an existing PCI device should return 0.
Because that's what my Power Mac 8600 returns when I run my Open Firmware lspci command.
Any bus/device/function that doesn't exist returns FF and won't be listed by lspci.
Any registers that are unused will show as 00 in the lspci output.
Make grackle log bus:device.function @register.size in all cases.
setenv doesn't allow entering strings that include multiple lines which is useful for nvramrc.
nvedit uses CTRL-C to end editing, like Open Firmware. It does not support deleting characters from a line or editing previous lines or any other special keys. It doesn't have nvstore or nvquit or nvrecover commands. Basically, you should edit your nvramrc in a text editor, then copy and paste into the debugger.
- Allow changing integer variables. Previously they could not be changed.
- Allow changing string variables. Previously they could only be changed if their length increased.
- printenv had a bug with strings longer than 32 characters.
- printenv now translates carriage return (used in nvramrc) as endl (which should perform carriage return and linefeed)
- For integers, setenv assumes decimal number input but if that fails it will try hex conversion. 0x prefix for hex numbers is optional unless the number only has digits 0 - 9.
- setenv converts linefeed to carriage return for string variables. nvramrc requires this for proper editing in Open Firmware.
- Added Open Firmware 2.4 nvram field names to OfNvramHdr comments.
- increase delay to 800 consecutive characters (reduces times when Open Firmware throws away pasted text)
- don't log the first sock read error (when accept hasn't been called yet) but do log sock read error if accept was called successfully already.
The expansion rom base register indicates the size of the expansion rom by the number of bits that remain zero after code attempts to set them all to 1. For example, a result of fffe0000 means 128K. The 11 least significant bits are ignored in the size calculation, which means the minimum rom size is indicated by fffff800 = 2K.
Handle the case where an expansion rom file might not have a size that is a multiple of 2 or is not greater than 2K.
Bytes between the end of the file and the end of the calculated rom size are set to 0xff.
Don't always return 0 when reading it. The status register contains some bits that Open Firmware uses to set some properties.
A PCI device can set a default status register value to set those bits.
this->status = 0x02B0; // 0000 0 01 0 1 0 1 1 0000 Capabilities List, 66 MHz, Fast Back-to-Back, DevSel Speed: Medium
For invalid or unsupported PCI accesses, do the following:
- log a device's full pci address using pciutils setpci command format bb:dd.f @rr.s (bus:device:function @register+offset.size).
- report as read or write access.
- log value for writes.
- bus, device, function, and register values cannot be determined from Invalid IDSEL values so they will output as ??.
- for invalid IDSEL values, report the entire value of the config_addr.
- for valid IDSEL values, the bus number cannot be determined since IDSEL only specifies device number. It's probably bus 00 but we'll show ?? to indicate an IDSEL type access.
Add missing config type read access logging for chaos.
With the option --serial_backend=socket, input and output to a serial port will use a SOCK_STREAM type UNIX domain socket. This allows you to do Open Firmware in one window, while the first window can be used for dingusppc debugger.
Other fixes:
- Added SIGTERM handler so that if the user force quits dingusppc, the terminal settings are properly restored. A user needs to force quit when --serial_backend=stdio and Open Firmware is taking input from ttya. If terminal settings are not restored, then running dingusppc after a force quit will cause Control-C to not work when --serial_backend is not stdio.
- Added a couple numbers to rcv_char_available - 15 is the number of consecutive characters that can processed. 400 is the total number of calls to rcv_char_available after 15 consecutive characters have been read before additional characters can be read. This delay in processing additional characters allows pasting arbitrarily large amounts of text into Open Firmware. A real serial port terminal app might have a text pacing option to limit the number of output characters per second but that is not an option since the emulator is not limiting character data to a baud rate.
Related Notes:
The socket file is created when dingusppc starts.
The socket file is named dingusppcsocket and is created in the current working directory (usually where the executable is located and where the dingusppc.log, nvram.bin, and pram.bin files are created).
The socket file is not visible in the Finder. You can see it in the terminal using the ls command.
The socket file can be used with the following command in a new terminal window:
socat UNIX-CLIENT:dingussocket -,cs8,parenb=0,echo=0,icanon=0,isig=0,icrnl=0
When dingusppc quits, the socat command ends.
Other notes:
The dingusppc --debugger option causes dingusppc to enter the debugger before Open Firmware outputs anything. You can connect to the socket while dingusppc is in the debugger. Then enter the go command to leave the debugger and start Open Firmware. However, since the startup sound takes a long time, you can probably connect to the socket before Open Firmware starts even without the --debugger option. It's like with a real Power Mac - you have a few seconds to hold Command-Option-O-F except in this case you have a few seconds to press the up arrow and press enter (for executing the last command from the terminal command history) and if you do it too late you'll still get into Open Firmware if auto-boot? was previously set to false using the dingusppc debugger which is actually the only way to get into Open Firmware since a keyboard is currently not emulated?).
To set ttya as the input and output device in Open Firmware, you can use the setenv command in the dingusppc debugger. The device path needs to be longer than the current device path (because code for handling shortening of the paths is currently not implemented). For example, ttya can replace kbd for the input-device, but to replace screen for the output-device you need to add some extra characters like this: ttya,11 (I think the number is for baud but we're not using a real serial port so baud doesn't matter).
Future ideas:
- Have dingusppc execute the socat command for you so that it opens a terminal window before Open Firmware starts.
- Add another --serial_backend for the printer port (ttyb) since now we have more than one type of serial backend. If both serial ports use socket backend, then a different name for the second socket is required.
- Have an option to make dingusppc block until something connects to the socket (this means calling accept after listen instead of after select).
- Test compatibility with serial port socket created by Parallels Desktop virtual machines in macOS.
- Find a solution that works with Windows.
- Test with Linux.
- Create a serial_backend type for tty devices. I suppose maybe socat can pipe the file socket to tty but a direct connection might be easier to setup.
- Allow using a socket created by some other app (for example, socat UNIX-LISTEN). This means dingusppc will assume the client role and will call connect instead of accept.
