tree 40bfceab01cc1c6a035eb66792638149400db1ef
parent 0740fd2914d9a567568981c5c1843174216803ae
parent b001227e5da2971f66776f211cc3e42c2ec5e87c
author Tom Rini <trini@konsulko.com> 1743702218 -0600
committer Tom Rini <trini@konsulko.com> 1743702218 -0600

Merge patch series "x86: Improve operation under QEMU"

Simon Glass <sjg@chromium.org> says:

U-Boot can start and boot an OS in both qemu-x86 and qemu-x86_64 but it
is not perfect.

With both builds, executing the VESA ROM causes an intermittent hang, at
least on some AMD CPUs.

With qemu-x86_64 kvm cannot be used since the move to long mode (64-bit)
is done in a way that works on real hardware but not with QEMU. This
means that performance is 4-5x slower than it could be, at least on my
CPU.

We can work around the first problem by using Bochs, which is anyway a
better choice than VESA for QEMU. The second can be addressed by using
the same descriptor across the jump to long mode.

With an MTRR fix this allows booting into Ubuntu on qemu-x86_64

In v3 some e820 patches are included to make booting reliable and avoid
ACPI tables being dropped. Also, several MTTR problems are addressed, to
support memory sizes above 4GB reliably.

Link: https://lore.kernel.org/all/20250315142643.2600605-1-sjg@chromium.org/