tree 7a14645dee60e41dcd67f1bea3c677fe3f38891f
parent c0512454405e854140a8d86a31a455d7946b50ee
author Daniel Verkamp <dverkamp@chromium.org> 1696280755 -0700
committer crosvm LUCI <crosvm-scoped@luci-project-accounts.iam.gserviceaccount.com> 1696355786 +0000

x86_64: only read bzImage setup_header, not all of boot_params

The Linux x86 64-bit Boot Protocol documentation specifies that a
bootloader should initialize a cleared (zeroed) boot_params structure
and only read the setup_header area from the bzImage file.

This ensures that all unknown fields in boot_params will be initialized
to zero, including the `sentinel` field used in the sanitize_boot_params
function to detect broken bootloaders. With this change applied, crosvm
no longer needs the sanitization workaround (validated by inserting an
undefined instruction into the sanitize_boot_params kernel function).

Additionally, the `e820_entries` field will always start at 0 due to the
default initialization of boot_params, which ensures we fill the
`e820_table` array from the beginning.

<https://www.kernel.org/doc/Documentation/x86/boot.txt>

BUG=b:303128596
TEST=tools/dev_container tools/presubmit
TEST=boot x86-64 bzImage kernel (Linux 6.6-rc4)

Change-Id: If9d40e335881f6862a5c9b25ef3187617f18a57a
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4906858
Reviewed-by: Dennis Kempin <denniskempin@google.com>
Reviewed-by: Morg <morg@google.com>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>