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Aaron Rainbolt
587db89afc
Xen traditionally allows customizing guest behavior by passing arguments to the VM kernel via the kernel command line. This is no longer possible when using GRUB with Xen, as the kernel command line is decided by the GRUB configuration file within the guest, not data passed to the guest by Xen. To work around this limitation, enable GRUB to parse a command line passed to it by Xen, and expose data from the command line to the GRUB configuration as environment variables. These variables can be used in the GRUB configuration for any desired purpose, such as extending the kernel command line passed to the guest. The command line format is inspired by the Linux kernel's command line format. To reduce the risk of misuse, abuse, or accidents in production, the command line will only be parsed if it consists entirely of 7-bit ASCII characters, only alphabetical characters and underscores are permitted in variable names, and all variable names must start with the string "xen_grub_env_". This also allows room for expanding the command line arguments accepted by GRUB in the future, should other arguments end up becoming desirable in the future. Signed-off-by: Aaron Rainbolt <arraybolt3@gmail.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>