mirror of
https://github.com/taigrr/gopher-os
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8dfc5d4e92
By setting up pwd as a Go workspace, we can trim import paths from something like "github.com/achilleasa/gopher-os/kernel" to just "kernel". These changes make forking easier and also allows us to move the code to a different git hosting provider without having to rewrite the imports.
36 lines
1.2 KiB
Go
36 lines
1.2 KiB
Go
package vmm
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import (
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"gopheros/kernel"
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"gopheros/kernel/mem"
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)
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var (
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// earlyReserveLastUsed tracks the last reserved page address and is
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// decreased after each allocation request. Initially, it points to
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// tempMappingAddr which coincides with the end of the kernel address
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// space.
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earlyReserveLastUsed = tempMappingAddr
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errEarlyReserveNoSpace = &kernel.Error{Module: "early_reserve", Message: "remaining virtual address space not large enough to satisfy reservation request"}
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)
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// EarlyReserveRegion reserves a page-aligned contiguous virtual memory region
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// with the requested size in the kernel address space and returns its virtual
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// address. If size is not a multiple of mem.PageSize it will be automatically
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// rounded up.
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//
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// This function allocates regions starting at the end of the kernel address
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// space. It should only be used during the early stages of kernel initialization.
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func EarlyReserveRegion(size mem.Size) (uintptr, *kernel.Error) {
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size = (size + (mem.PageSize - 1)) & ^(mem.PageSize - 1)
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// reserving a region of the requested size will cause an underflow
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if uintptr(size) > earlyReserveLastUsed {
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return 0, errEarlyReserveNoSpace
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}
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earlyReserveLastUsed -= uintptr(size)
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return earlyReserveLastUsed, nil
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}
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