This should be a fairly easy merge, assuming I didn’t mess anything up. TL:DR no one uses it and it’s not great.
Boot from DVD Backup is an ancient feature with origins in the Megacommit. Back then, GameCube and Wii games were quite large relative to drives of the time. For example, in 2008, the most common hard drive sizes were 320GB and 512GB. On the 320GB drive I personally had at the time, as little as 42 Wii ISOs could have filled it entirely! And that’s ignoring any other files one might want to put onto a drive. Backup DVDs allowed users to burn relatively cheap DVD media and store their GameCube and Wii dumps in a Dolphin accessible way that didn’t eat into their precious HDD space. It had compromises, even then, but in 2008… I mean honestly users probably wouldn’t even notice those compromises with how Dolphin barely even worked at all back then.
Obviously, today the storage space concerns are not as big of an issue. According to seagate the average hard drive it sells today is 8TB. For typical laptops purchased now, the -minimum- selection for storage is usually 1TB. You can even buy a name brand 4TB external hard drive for $100. GC and Wii ISOs are not as big as they once were, relatively anyway. Plus flash drives and SD cards are super cheap and way faster than disc drives ever were. For anyone that has limited drive space, removable flash media can fulfill this offloading role far better than backup DVD media ever could.
Also no one has DVD drives anymore. That’s kind of an important detail.
But to see if Booting from DVD Backup even still worked, I decided to give it a try. I have an ASUS BW-16D1HT, a badass Bluray XL reading and burning drive, connected to my Windows 11 Threadripper 5975WX machine. A super fast drive on a super fast machine is as good as it possibly can get for this feature. So I bought a spindle of DVD-Rs, burned a couple of discs and gave it a try. Surprisingly, it does still work. However, as expected, it introduces a lot of stuttering. Testing Prime 1 and Prime 3, in both games stuttering was introduced whenever the DVD Drive had to suddenly seek. Spikes of 50ms occurred constantly, but I observed 150ms and even over 1000ms stutters! The worst was a three second stutter, when loading Elysia in Prime 3. I could even hear the stutters - any time the drive suddenly made a harsh seeking noise, the game would have a hard stutter. It worked but, it has some serious compromises.
Boot from DVD Backup isn’t great, using removable flash media or external hard drives is a FAR better option for anyone with limited storage space today, and no one can even use this feature anymore because their computers don’t even have disc drives. It’s time for Boot from DVD Backup to go!
So I did my best on the cleanup but I’m bound to have left some bits. Especially in translation - I didn’t get any warnings or anything there that could help point me to where to clean that up. Please review!
For a few years now, I've been thinking it would be nice to make Dolphin
support reading Wii games in the format they come in when you download
them from the Wii U eShop. The Wii U eShop has some good deals on Wii
games (Metroid Prime Trilogy especially is rather expensive if you try
to buy it physically!), and it's the only place right now where you can
buy Wii games digitally.
Of course, Nintendo being Nintendo, next year they're going to shut down
this only place where you can buy Wii games digitally. I kind of wish I
had implemented this feature earlier so that people would've had ample
time to buy the games they want, but... better late than never, right?
I used MIT-licensed code from the NOD library as a reference when
implementing this. None of the code has been directly copied, but
you may notice that the names of the struct members are very similar.
c1635245b8/lib/DiscIONFS.cpp
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
This lets VolumeDirectory/DirectoryBlob skip implementing
various volume functions like GetGameID, GetBanner, etc.
It also lets us view extracted discs in the game list.
This ends up breaking the boot process for Wii
DirectoryBlobs due to workarounds being removed from the
boot process, but that will be fixed later by adding
proper DirectoryBlob support for things like TMDs.
We now expect the directories to be laid out in a certain
format (based on the format that WIT uses) instead of requiring
the user to set the DVD root and apploader path settings.
DriveReader::m_size was never initialized which was indirectly
causing CGameListCtrl to crash Dolphin when it tried to insert a
character at a negative index in a string.
Reading one sector at a time is very inefficient and appears to
be causing timing issues during boot so SectorReader has been
enhanced to support batching.
SectorReader has been given a working cache system.
Rather than rely on the developer to do the right thing,
just make the default behavior safely deallocate resources.
If shared semantics are ever needed in the future, the
constructor that takes a unique_ptr for shared_ptr can
be used.
Tilka