62 lines
2.5 KiB
Diff
62 lines
2.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Javier Martinez Canillas <javierm@redhat.com>
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Date: Sat, 7 Nov 2020 01:03:18 +0100
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Subject: [PATCH] docs: Document the cutmem command
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The command is not present in the docs/grub.texi user documentation.
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Reported-by: Daniel Kiper <daniel.kiper@oracle.com>
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Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
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Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
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Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
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---
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docs/grub.texi | 21 +++++++++++++++++++++
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1 file changed, 21 insertions(+)
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diff --git a/docs/grub.texi b/docs/grub.texi
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index c55452307..314bbeb84 100644
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--- a/docs/grub.texi
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+++ b/docs/grub.texi
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@@ -3942,6 +3942,7 @@ you forget a command, you can run the command @command{help}
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* cpuid:: Check for CPU features
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* crc:: Compute or check CRC32 checksums
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* cryptomount:: Mount a crypto device
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+* cutmem:: Remove memory regions
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* date:: Display or set current date and time
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* devicetree:: Load a device tree blob
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* distrust:: Remove a pubkey from trusted keys
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@@ -4103,6 +4104,8 @@ this page is to be filtered. This syntax makes it easy to represent patterns
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that are often result of memory damage, due to physical distribution of memory
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cells.
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+The command is similar to @command{cutmem} command.
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+
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Note: The command is not allowed when lockdown is enforced (@pxref{Lockdown}).
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This prevents removing EFI memory regions to potentially subvert the
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security mechanisms provided by the UEFI secure boot.
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@@ -4266,6 +4269,24 @@ GRUB suports devices encrypted using LUKS and geli. Note that necessary modules
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be used.
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@end deffn
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+@node cutmem
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+@subsection cutmem
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+
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+@deffn Command cutmem from[K|M|G] to[K|M|G]
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+Remove any memory regions in specified range.
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+@end deffn
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+
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+This command notifies the memory manager that specified regions of RAM ought to
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+be filtered out. This remains in effect after a payload kernel has been loaded
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+by GRUB, as long as the loaded kernel obtains its memory map from GRUB. Kernels
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+that support this include Linux, GNU Mach, the kernel of FreeBSD and Multiboot
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+kernels in general.
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+
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+The command is similar to @command{badram} command.
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+
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+Note: The command is not allowed when lockdown is enforced (@pxref{Lockdown}).
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+ This prevents removing EFI memory regions to potentially subvert the
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+ security mechanisms provided by the UEFI secure boot.
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@node date
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@subsection date
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