Only perform a single TLB flush after identity mapping #265
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This commit changes the BIOS bootloader to only flush the TLB once, after it has identity-mapped every physical memory frame. This should be a bit more efficient, as we don't perform a separate `invlpg` for every page table entry we create, and instead only flush the entire thing by reloading `CR3` when we're actually ready to use it. This is based on a suggestion by @phil-opp, here: rust-osdev#260 (comment) This change doesn't actually seem to make all that big an impact in boot times on QEMU v7.1 on its own, relative to PR rust-osdev#260, but it might make an additional improvement on top of that PR.
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This commit changes the BIOS bootloader to only flush the TLB once, after it has identity-mapped every physical memory frame. This should be a bit more efficient, as we don't perform a separate
invlpgfor every page table entry we create, and instead only flush the entire thing by reloadingCR3when we're actually ready to use it.This is based on a suggestion by @phil-opp, here:
#260 (comment)
This change doesn't actually seem to make all that big an impact in boot times on QEMU v7.1 on its own, relative to PR #260, but it might make an additional improvement on top of that PR.