1From f05e79a0143beb2d9a482a3ebf4fe0ce76778122 Mon Sep 17 00:00:00 2001 2From: Javier Martinez Canillas <javierm@redhat.com> 3Date: Sat, 7 Nov 2020 01:03:18 +0100 4Subject: [PATCH] docs: Document the cutmem command 5 6The command is not present in the docs/grub.texi user documentation. 7 8Reported-by: Daniel Kiper <daniel.kiper@oracle.com> 9Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> 10Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com> 11Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> 12Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com> 13--- 14 docs/grub.texi | 21 +++++++++++++++++++++ 15 1 file changed, 21 insertions(+) 16 17diff --git a/docs/grub.texi b/docs/grub.texi 18index 79f58c5..8518cc0 100644 19--- a/docs/grub.texi 20+++ b/docs/grub.texi 21@@ -3892,6 +3892,7 @@ you forget a command, you can run the command @command{help} 22 * cpuid:: Check for CPU features 23 * crc:: Compute or check CRC32 checksums 24 * cryptomount:: Mount a crypto device 25+* cutmem:: Remove memory regions 26 * date:: Display or set current date and time 27 * devicetree:: Load a device tree blob 28 * distrust:: Remove a pubkey from trusted keys 29@@ -4051,6 +4052,8 @@ this page is to be filtered. This syntax makes it easy to represent patterns 30 that are often result of memory damage, due to physical distribution of memory 31 cells. 32 33+The command is similar to @command{cutmem} command. 34+ 35 Note: The command is not allowed when lockdown is enforced (@pxref{Lockdown}). 36 This prevents removing EFI memory regions to potentially subvert the 37 security mechanisms provided by the UEFI secure boot. 38@@ -4214,6 +4217,24 @@ GRUB suports devices encrypted using LUKS and geli. Note that necessary modules 39 be used. 40 @end deffn 41 42+@node cutmem 43+@subsection cutmem 44+ 45+@deffn Command cutmem from[K|M|G] to[K|M|G] 46+Remove any memory regions in specified range. 47+@end deffn 48+ 49+This command notifies the memory manager that specified regions of RAM ought to 50+be filtered out. This remains in effect after a payload kernel has been loaded 51+by GRUB, as long as the loaded kernel obtains its memory map from GRUB. Kernels 52+that support this include Linux, GNU Mach, the kernel of FreeBSD and Multiboot 53+kernels in general. 54+ 55+The command is similar to @command{badram} command. 56+ 57+Note: The command is not allowed when lockdown is enforced (@pxref{Lockdown}). 58+ This prevents removing EFI memory regions to potentially subvert the 59+ security mechanisms provided by the UEFI secure boot. 60 61 @node date 62 @subsection date 63-- 642.14.2 65 66