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64-bit dynamic_x86 (patch)

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Reply 20 of 123, by jmarsh

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AFAIK the difference between 1 and 2 is that memory returned by brk() will be randomized at the higher level.
Data segments can't be randomized as the text segments contain fixed RIP-relative offsets to them.

Reply 21 of 123, by kjliew

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krcroft wrote:

kjliew, does disabling randomization of the virtual address space help?

I am not interested in tinkering with kernel to get things work. The core should be able to handle any forms of the CPU instructions dealing with relative and absolute offsets.

Several observation so far:
- Real mode codes are usually OK, even dynamic core was forced to run at the beginning. GODS played over 2 Worlds at Level 1. However, DUNE2 will error out with the same issue. DUNE2 is purely real mode code, but make use of EMS memory.
- DOS4G/DOS4GW is almost certain that the error will show up, perhaps within the setting up of protected-mode stub.
- CWSDPMI is OK. Quake1 will run, but at some point of time, it will error out.

@krcsoft, were you able to run any DOS4G/DOS4GW games without replacing the stub on your Core i7-6700K, for eg. WarCraft?

@jmarsh, the error is rarely reproducible on Windows. Did you get a chance to reproduce it consistently to address the issue?

Reply 23 of 123, by krcroft

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kjliew wrote:

@krcroft, were you able to run any DOS4G/DOS4GW games without replacing the stub on your Core i7-6700K, for eg. WarCraft?

kjliew, I unfortunately wasn't able to reproduce any crashes or failures, regardless of kernel.randomize_va_space set to 0 or 2. I've tried:
- Space Hulk with dos4gw.exe 1.92 and 2.01a
- Redneck Rampage with 1.97 and 2.01a
- Warcraft I with 2.01a
- Warcraft II, with war2.exe's stub replaced with dos32a 9.1.2

Reply 24 of 123, by kjliew

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krcroft wrote:

kjliew, I unfortunately wasn't able to reproduce any crashes or failures, regardless of kernel.randomize_va_space set to 0 or 2.

Thanks. I would expect similar results since my Core i7-6600U laptop does not show any error, too.

Reply 25 of 123, by jmarsh

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You need to test games that use self-modifying code, which causes hostmem to get accessed directly by the emitted code (for frequently modified instructions). Games using the Build engine are the most common example so if RR didn't trigger it you likely won't have an issue.
There's not much point going further into it now anyway, the way the code cache is allocated needs to be switched from malloc to mmap (since using mprotect on malloc'd memory is not meant to be done) and that can affect the returned address.

Reply 26 of 123, by kjliew

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jmarsh wrote:

You need to test games that use self-modifying code, which causes hostmem to get accessed directly by the emitted code (for frequently modified instructions). Games using the Build engine are the most common example so if RR didn't trigger it you likely won't have an issue.

For the problematic Intel Haswell CPU and ArchLinux (and I presumed the same for most of the Linux distro with recent kernel), it only takes a simple DOS4GW application to reproduce the error. In my case, a simple TEST04 from the 3Dfx Glide2 SDK demo would be suffice. I am pretty sure the code is not self-modifying. PCPBENCH is another good one. The bad RIP address error reproduces easily and consistently.

@Dominus had an even worst error scenario with MacOS that just by switching the core in the DOSBox command prompt would trigger the bad RIP address error, which I couldn't reproduce on ArchLinux. Since it's on MacOS, it got to be an Intel CPU, but there wasn't further details about the Intel CPU family.

Anyway, let's see if the mmap allocation would fix the issue for all. I am looking forward to the next patch update.

Reply 27 of 123, by Dominus

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After Jmarsh told me to replace the first line of gen_jmp_ptr() with this: "opcode(0).set64().setimm((Bitu)ptr,8).Emit8Reg(0xA1);" I had no more crash and extreme speed gain.

Windows 3.1x guide for DOSBox
60 seconds guide to DOSBox

Reply 31 of 123, by Dominus

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From the first post:

Results look good; a huge speed boost over current 64-bit builds and around 10-20% improvement over 32-bit dyn_x86.

Windows 3.1x guide for DOSBox
60 seconds guide to DOSBox

Reply 32 of 123, by hail-to-the-ryzen

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The post did not distinguish testing on 32-bit OS versus 64-bit OS. It leads to errors in the former case in my build, but requires further checks to submit a useful report.

Reply 34 of 123, by hail-to-the-ryzen

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Not yet, I haven't tested enough. I would have to have a better control build. Warcraft 2 runs but Quake led to a page fault on startup.

Thank you for the great contribution with this cpu core.

Reply 37 of 123, by hail-to-the-ryzen

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Verified that the r4252 commit is present. The 32-bit build works now, but by undefining X86_DYNFPU_DH_ENABLED and using a non-x86 fpu interpreter core instead. It runs significantly slower in this non-standard configuration than the previous dynamic x86 cpu core in 32-bit Windows.

It seems that there are not many changes to the 32-bit dynamic x86 core with this core apart from reducing redundant x86 fpu code.