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The videoinfo command will initialize all non-active video adapters. Video drivers tend to zero out the global framebuffer object on initialization. This is not a problem when there is no active video adapter. However, when there is, then outputting to the video adapter will cause a crash because methods in the framebuffer object are reinitialized. For example, this command sequence will cause a crash. terminal_output --append gfxterm; videoinfo When running in a QEMU headless with GRUB built for the x86_64-efi target, the first command initializes the Bochs video adapter, which, among other things, sets the set_page() member function. Then when videoinfo is run, all non-Bochs video adapters will be initialized, each one wiping the framebuffer and thus setting set_page to NULL. Soon after the videoinfo command finishes there will be a call to grub_refresh(), which will ultimately call the framebuffer's set_page which will be NULL and cause a crash when called. Signed-off-by: Glenn Washburn <development@efficientek.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'