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aarch64: Reduce UEFI space size to 4 MiB

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UEFI need to be loaded to a flash area at the beginning of guest memory
address space. To simulate the flash, we take a piece of RAM and hide
it to the guest. As this is a temporary solution, the hiden RAM for UEFI
should be as little as possible. The size was 64 MiB, that's too much,
4 MiB is enough.

The down side of such simulation is that there is a gap (4 MiB) between
the memory size in VMM's view and that in guest's view. This is to be
fixed by implementing a flash device in future.

Signed-off-by: Michael Zhao <michael.zhao@arm.com>
This commit is contained in:
Michael Zhao 2021-06-24 09:57:01 +08:00 committed by Rob Bradford
parent d4d62fc9dc
commit 45c4d1a06e
2 changed files with 6 additions and 5 deletions
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5
arch/src/aarch64/layout.rs
View File

@ -46,10 +46,11 @@
use vm_memory::GuestAddress;
/// 0x0 ~ 0x400_0000 is reserved to uefi
/// 0x0 ~ 0x40_0000 (4 MiB) is reserved to UEFI
/// UEFI binary size is required less than 3 MiB, reserving 4 MiB is enough.
pub const UEFI_START: u64 = 0x0;
pub const MEM_UEFI_START: GuestAddress = GuestAddress(0);
pub const UEFI_SIZE: u64 = 0x0400_0000;
pub const UEFI_SIZE: u64 = 0x040_0000;
/// Below this address will reside the GIC, above this address will reside the MMIO devices.
pub const MAPPED_IO_START: u64 = 0x0900_0000;

6
arch/src/aarch64/mod.rs
View File

@ -88,7 +88,7 @@ pub fn configure_vcpu(
pub fn arch_memory_regions(size: GuestUsize) -> Vec<(GuestAddress, usize, RegionType)> {
// Normally UEFI should be loaded to a flash area at the beginning of memory.
// But now flash memory type is not supported.
// As a workaround, we take 64 MiB memory from the main RAM for UEFI.
// As a workaround, we take 4 MiB memory from the main RAM for UEFI.
// As a result, the RAM that the guest can see is less than what has been
// assigned in command line, when ACPI and UEFI is enabled.
let ram_deduction = if cfg!(feature = "acpi") {
@ -98,7 +98,7 @@ pub fn arch_memory_regions(size: GuestUsize) -> Vec<(GuestAddress, usize, Region
};
vec![
// 0 ~ 64 MiB: Reserved for UEFI space
// 0 ~ 4 MiB: Reserved for UEFI space
#[cfg(feature = "acpi")]
(GuestAddress(0), layout::UEFI_SIZE as usize, RegionType::Ram),
#[cfg(not(feature = "acpi"))]
@ -107,7 +107,7 @@ pub fn arch_memory_regions(size: GuestUsize) -> Vec<(GuestAddress, usize, Region
layout::UEFI_SIZE as usize,
RegionType::Reserved,
),
// 64 MiB ~ 256 MiB: Gic and legacy devices
// 4 MiB ~ 256 MiB: Gic and legacy devices
(
GuestAddress(layout::UEFI_SIZE),
(layout::MEM_32BIT_DEVICES_START.0 - layout::UEFI_SIZE) as usize,