887f98f0db
Currently, all platforms will set up their heap on initialization of the platform code. While this works mostly fine, it poses some limitations on memory management on us. Most notably, allocating big chunks of memory in the gigabyte range would require us to pre-request this many bytes from the firmware and add it to the heap from the beginning on some platforms like EFI. As this isn't needed for most configurations, it is inefficient and may even negatively impact some usecases when, e.g., chainloading. Nonetheless, allocating big chunks of memory is required sometimes, where one example is the upcoming support for the Argon2 key derival function in LUKS2. In order to avoid pre-allocating big chunks of memory, this commit implements a runtime mechanism to add more pages to the system. When a given allocation cannot be currently satisfied, we'll call a given callback set up by the platform's own memory management subsystem, asking it to add a memory area with at least "n" bytes. If this succeeds, we retry searching for a valid memory region, which should now succeed. If this fails, we try asking for "n" bytes, possibly spread across multiple regions, in hopes that region merging means that we end up with enough memory for things to work out. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Daniel Axtens <dja@axtens.net> Tested-by: Stefan Berger <stefanb@linux.ibm.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> Tested-by: Patrick Steinhardt <ps@pks.im>
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'