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Merged
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May 12, 2025
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Update linux.Map_Flags_Bits #5152

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dec3d69
Update `linux.Map_Flags_Bits`
Kelimion May 12, 2025
be24feb
Move things to constants.odin
Kelimion May 12, 2025
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Update linux.Map_Flags_Bits 
Fixes #5151

- Removes `SHARED_VALIDATE` from the enum and turns it into `Map_Shared_Validate :: Map_Flags{.SHARED, .PRIVATE}` so it has the proper value of 0x03.
- Adds `DROPPABLE`.
- Adds constants `MAP_HUGE_SHIFT` and `MAP_HUGE_MASK`.
- Adds the huge page precomputed constants from `mman.h`, defined as the log2 of the size shifted left by `MAP_HUGE_SHIFT`:
	Map_Huge_16KB
	Map_Huge_64KB
	Map_Huge_512KB
	Map_Huge_1MB
	Map_Huge_2MB
	Map_Huge_8MB
	Map_Huge_16MB
	Map_Huge_32MB
	Map_Huge_256MB
	Map_Huge_512MB
	Map_Huge_1GB
	Map_Huge_2GB
	Map_Huge_16GB
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@Kelimion
Kelimion committed May 12, 2025
commit dec3d6959df1a7a876782f3e233d0320d41a0fad
8 changes: 6 additions & 2 deletions core/sys/linux/bits.odin
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Original file line number Diff line number Diff line change
Expand Up @@ -579,7 +579,7 @@ Inotify_Event_Bits :: enum u32 {
/*
Bits for Mem_Protection bitfield
*/
Mem_Protection_Bits :: enum{
Mem_Protection_Bits :: enum {
READ = 0,
WRITE = 1,
EXEC = 2,
Expand All @@ -598,7 +598,7 @@ Mem_Protection_Bits :: enum{
Map_Flags_Bits :: enum {
SHARED = 0,
PRIVATE = 1,
SHARED_VALIDATE = 2,
DROPPABLE = 3,
FIXED = 4,
ANONYMOUS = 5,
// platform-dependent section start
Expand All @@ -619,6 +619,10 @@ Map_Flags_Bits :: enum {
UNINITIALIZED = 26,
}

// Not actually flags, but a shift and mask for when HUGETLB is defined
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These should go into constants.odin and prob good to stay consistent with the comment style used in the package.

MAP_HUGE_SHIFT :: 26
MAP_HUGE_MASK :: 63

/*
Bits for MLock_Flags
*/
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15 changes: 15 additions & 0 deletions core/sys/linux/types.odin
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Expand Up @@ -371,6 +371,21 @@ Mem_Protection :: bit_set[Mem_Protection_Bits; i32]
*/
Map_Flags :: bit_set[Map_Flags_Bits; i32]

Map_Shared_Validate :: Map_Flags{.SHARED, .PRIVATE}
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These are constants right? Should go into constants.odin and be in upper snake case.

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That's not very usable, though. Who's going to look for Map_Shared_Validate in constants.odin instead of next to either the enum or the bit_set?

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@Kelimion Kelimion May 12, 2025 •
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And when it comes to os.open flag combinations, we don't put them in another file either.

File_Flags :: distinct bit_set[File_Flag; uint]
File_Flag :: enum {
	Read,
	Write,
	Append,
	Create,
	Excl,
	Sync,
	Trunc,
	Sparse,
	Inheritable,

	Unbuffered_IO,
}

O_RDONLY  :: File_Flags{.Read}
O_WRONLY  :: File_Flags{.Write}
O_RDWR    :: File_Flags{.Read, .Write}
O_APPEND  :: File_Flags{.Append}
O_CREATE  :: File_Flags{.Create}
O_EXCL    :: File_Flags{.Excl}
O_SYNC    :: File_Flags{.Sync}
O_TRUNC   :: File_Flags{.Trunc}
O_SPARSE  :: File_Flags{.Sparse}

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I mean that's how the entirety of this package is structured

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@Kelimion Kelimion May 12, 2025 •
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True. The core:os/os2 way is much more convenient, but it's also much newer.

I'll make it UPPER_SNAKE_CASE and move it to constants.odin for consistency, but leave a comment under the bit_set in types.odin that some precomputed huge page sizes are available over there.

We may at some point want to give core:sys the core:os/os2 convenience treatment and keep related info together.

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Right, I am not saying I fully agree with the structure here but to be at least consistent on the package level is a good thing.

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I made the changes and left a comment where to find it for people who expect it next to the enum or bit_set.

Map_Huge_16KB :: transmute(Map_Flags)(u32(14) << MAP_HUGE_SHIFT)
Map_Huge_64KB :: transmute(Map_Flags)(u32(16) << MAP_HUGE_SHIFT)
Map_Huge_512KB :: transmute(Map_Flags)(u32(19) << MAP_HUGE_SHIFT)
Map_Huge_1MB :: transmute(Map_Flags)(u32(20) << MAP_HUGE_SHIFT)
Map_Huge_2MB :: transmute(Map_Flags)(u32(21) << MAP_HUGE_SHIFT)
Map_Huge_8MB :: transmute(Map_Flags)(u32(23) << MAP_HUGE_SHIFT)
Map_Huge_16MB :: transmute(Map_Flags)(u32(24) << MAP_HUGE_SHIFT)
Map_Huge_32MB :: transmute(Map_Flags)(u32(25) << MAP_HUGE_SHIFT)
Map_Huge_256MB :: transmute(Map_Flags)(u32(28) << MAP_HUGE_SHIFT)
Map_Huge_512MB :: transmute(Map_Flags)(u32(29) << MAP_HUGE_SHIFT)
Map_Huge_1GB :: transmute(Map_Flags)(u32(30) << MAP_HUGE_SHIFT)
Map_Huge_2GB :: transmute(Map_Flags)(u32(31) << MAP_HUGE_SHIFT)
Map_Huge_16GB :: transmute(Map_Flags)(u32(34) << MAP_HUGE_SHIFT)

/*
Flags for mlock(2).
*/
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