Documentation: Update the default value of crashkernel low

In commit 94fb933 ("x86/crash: Allocate enough low memory when
crashkernel=high") the default value of crashkernel low memory
is changed to 256M. In this patch update it accordingly.

Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 22a4b687ea5b4b3cb9d576bfeffaed813256a795..945bc0de7f0750acefae3f89695c9b1b510b18be 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -789,8 +789,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        is passed, kernel could allocate physical memory region
                        above 4G, that cause second kernel crash on system
                        that require some amount of low memory, e.g. swiotlb
-                       requires at least 64M+32K low memory.  Kernel would
-                       try to allocate 72M below 4G automatically.
+                       requires at least 64M+32K low memory, also enough extra
+                       low memory is needed to make sure DMA buffers for 32-bit
+                       devices won't run out. Kernel would try to allocate at
+                       at least 256M below 4G automatically.
                        This one let user to specify own low range under 4G
                        for second kernel instead.
                        0: to disable low allocation.