Re: Reserving physical memory at boot time

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > Really? So user has to know where ACPI tables are and specify less
> > than that on mem= command line? That seems very
> > counter-intuitive. [Ahha, its probaly okay because e820 saves you.]
> > 
> > What do you pass on 4GB machine as mem= parameter? AFAIK those beasts
> > have hole at 3.75G. [Hopefully bigmem machines have working e820
> > tables?]
> > 
> 
> If you pass mem= you have to pass mem=3840M.  Yes, it sucks, but if you
> genuinely have a machine which is so fucked up that you can't rely on
> the memory map the BIOS presents to you, you have problems to begin with.
> 
> Oh yes, this is why GRUB passing the mem= parameter gratuitously was
> beyond total and complete brainfuckage.

Okay; which mem= options you want killed?

What about this?
								Pavel

--- clean/arch/i386/kernel/setup.c	2003-03-06 23:25:14.000000000 +0100
+++ linux/arch/i386/kernel/setup.c	2003-03-08 00:18:21.000000000 +0100
@@ -527,6 +527,9 @@
 		 * to <mem>, overriding the bios size.
 		 * "mem=XXX[KkmM]@XXX[KkmM]" defines a memory region from
 		 * <start> to <start>+<mem>, overriding the bios size.
+		 *
+		 * HPA tells me bootloaders need to parse mem=, so no new
+		 * option should be mem=
 		 */
 		if (c == ' ' && !memcmp(from, "mem=", 4)) {
 			if (to != command_line)
@@ -535,8 +538,24 @@
 				from += 9+4;
 				clear_bit(X86_FEATURE_PSE, boot_cpu_data.x86_capability);
 				disable_pse = 1;
-			} else if (!memcmp(from+4, "exactmap", 8)) {
-				from += 8+4;
+			} else {
+				/* If the user specifies memory size, we
+				 * limit the BIOS-provided memory map to
+				 * that size. exactmap can be used to specify
+				 * the exact map. mem=number can be used to
+				 * trim the existing memory map.
+				 */
+				unsigned long long start_at, mem_size;
+ 
+				mem_size = memparse(from+4, &from);
+			}
+		}
+
+		if (c == ' ' && !memcmp(from, "memmap=", 7)) {
+			if (to != command_line)
+				to--;
+			if (!memcmp(from+7, "exactmap", 8)) {
+				from += 8+7;
 				e820.nr_map = 0;
 				userdef = 1;
 			} else {
@@ -548,7 +567,7 @@
 				 */
 				unsigned long long start_at, mem_size;
  
-				mem_size = memparse(from+4, &from);
+				mem_size = memparse(from+7, &from);
 				if (*from == '@') {
 					start_at = memparse(from+1, &from);
 					add_memory_region(start_at, mem_size, E820_RAM);
@@ -565,6 +584,7 @@
 			}
 		}
 
+
 		/* "acpi=off" disables both ACPI table parsing and interpreter init */
 		if (c == ' ' && !memcmp(from, "acpi=off", 8))
 			acpi_disabled = 1;


-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]