-#include "stdint.h"
-#include "stddef.h"
-#include "memsizes.h"
-#include "etherboot.h"
-#include "basemem.h"
-
-/* Routines to allocate base memory in a BIOS-compatible way, by
- * updating the Free Base Memory Size counter at 40:13h.
- *
- * Michael Brown <mbrown@fensystems.co.uk> (mcb30)
- *
- * We no longer have anything to do with the real-mode stack. The
- * only code that can end up creating a huge bubble of wasted base
- * memory is the UNDI driver, so we make it the responsibility of the
- * UNDI driver to reallocate the real-mode stack if required.
- */
-
-/* "fbms" is an alias to the BIOS FBMS counter at 40:13, and acts just
- * like any other uint16_t. We can't be used under -DKEEP_IT_REAL
- * anyway, so we may as well be efficient.
- */
-#define fbms ( * ( ( uint16_t * ) phys_to_virt ( 0x413 ) ) )
-#define FBMS_MAX ( 640 )
-
-/* Local prototypes */
-static void free_unused_base_memory ( void );
-
/*
- * Return amount of free base memory in bytes
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
*
- */
-unsigned int get_free_base_memory ( void ) {
- return fbms << 10;
-}
-
-/* Allocate N bytes of base memory. Amount allocated will be rounded
- * up to the nearest kB, since that's the granularity of the BIOS FBMS
- * counter. Returns NULL if memory cannot be allocated.
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
*
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
-void * alloc_base_memory ( size_t size ) {
- unsigned int size_kb = ( size + 1023 ) >> 10;
- void *ptr;
-
- DBG ( "Trying to allocate %d bytes of base memory from %d kB free\n",
- size, fbms );
-
- /* Free up any unused memory before we start */
- free_unused_base_memory();
- /* Check available base memory */
- if ( size_kb > fbms ) {
- DBG ( "Could not allocate %d kB of base memory: "
- "only %d kB free\n", size_kb, fbms );
- return NULL;
- }
+#include <stdint.h>
+#include <realmode.h>
+#include <bios.h>
+#include <basemem.h>
+#include <gpxe/hidemem.h>
- /* Reduce available base memory */
- fbms -= size_kb;
-
- /* Calculate address of memory allocated */
- ptr = phys_to_virt ( fbms << 10 );
-
- /* Zero out memory. We do this so that allocation of
- * already-used space will show up in the form of a crash as
- * soon as possible.
- *
- * Update: there's another reason for doing this. If we don't
- * zero the contents, then they could still retain our "free
- * block" markers and be liable to being freed whenever a
- * base-memory allocation routine is next called.
- */
- memset ( ptr, 0, size_kb << 10 );
-
- DBG ( "Allocated %d kB of base memory at [%4.4lx:0000,%4.4lx:0000), "
- "%d kB now free\n", size_kb,
- ( virt_to_phys ( ptr ) >> 4 ),
- ( ( virt_to_phys ( ptr ) + ( size_kb << 10 ) ) >> 4 ), fbms );
-
- /* Update our memory map */
- get_memsizes();
-
- return ptr;
-}
-
-/* Free base memory allocated by alloc_base_memory. The BIOS provides
- * nothing better than a LIFO mechanism for freeing memory (i.e. it
- * just has the single "total free memory" counter), but we improve
- * upon this slightly; as long as you free all the allocated blocks, it
- * doesn't matter what order you free them in. (This will only work
- * for blocks that are freed via free_base_memory()).
+/** @file
*
- * Yes, it's annoying that you have to remember the size of the blocks
- * you've allocated. However, since our granularity of allocation is
- * 1K, the alternative is to risk wasting the occasional kB of base
- * memory, which is a Bad Thing. Really, you should be using as
- * little base memory as possible, so consider the awkwardness of the
- * API to be a feature! :-)
+ * Base memory allocation
*
*/
-void free_base_memory ( void *ptr, size_t size ) {
- unsigned int remainder = virt_to_phys ( ptr ) & 1023;
- unsigned int size_kb = ( size + remainder + 1023 ) >> 10;
- union free_base_memory_block *free_block =
- ( ( void * ) ( ptr - remainder ) );
-
- if ( ( ptr == NULL ) || ( size == 0 ) ) {
- return;
- }
- DBG ( "Trying to free %d bytes base memory at %4.4lx:%4.4lx "
- "from %d kB free\n", size,
- ( virt_to_phys ( ptr - remainder ) >> 4 ),
- ( virt_to_phys ( ptr - remainder ) & 0xf ) + remainder,
- fbms );
-
- /* Mark every kilobyte within this block as free. This is
- * overkill for normal purposes, but helps when something has
- * allocated base memory with a granularity finer than the
- * BIOS granularity of 1kB. PXE ROMs tend to do this when
- * they allocate their own memory. This method allows us to
- * free their blocks (admittedly in a rather dangerous,
- * tread-on-anything-either-side sort of way, but there's no
- * other way to do it).
- *
- * Since we're marking every kB as free, there's actually no
- * need for recording the size of the blocks. However, we
- * keep this in so that debug messages are friendlier. It
- * probably adds around 8 bytes to the overall code size.
- */
- for ( ; size_kb > 0 ; free_block++, size_kb-- ) {
- /* Mark this block as unused */
- free_block->header.magic = FREE_BLOCK_MAGIC;
- free_block->header.size_kb = size_kb;
- }
-
- /* Free up unused base memory */
- free_unused_base_memory();
-
- /* Update our memory map */
- get_memsizes();
-}
-
-/* Do the actual freeing of memory. This is split out from
- * free_base_memory() so that it may be called separately. It
- * should be called whenever base memory is deallocated by an external
- * entity (if we can detect that it has done so) so that we get the
- * chance to free up our own blocks.
+/**
+ * Set the BIOS free base memory counter
+ *
+ * @v new_fbms New free base memory counter (in kB)
*/
-static void free_unused_base_memory ( void ) {
- union free_base_memory_block *free_block;
-
- /* Try to release memory back to the BIOS. Free all
- * consecutive blocks marked as free.
- */
- while ( 1 ) {
- /* Calculate address of next potential free block */
- free_block = phys_to_virt ( fbms << 10 );
-
- /* Stop processing if we're all the way up to 640K or
- * if this is not a free block
- */
- if ( ( fbms == FBMS_MAX ) ||
- ( free_block->header.magic != FREE_BLOCK_MAGIC ) ) {
- break;
- }
+void set_fbms ( unsigned int new_fbms ) {
+ uint16_t fbms = new_fbms;
- /* Return memory to BIOS */
- fbms += free_block->header.size_kb;
+ /* Update the BIOS memory counter */
+ put_real ( fbms, BDA_SEG, BDA_FBMS );
- DBG ( "Freed %ld kB of base memory at [%4.4lx:0000,%4.4lx:0000), "
- "%d kB now free\n",
- free_block->header.size_kb,
- ( virt_to_phys ( free_block ) >> 4 ),
- ( ( virt_to_phys ( free_block ) +
- ( free_block->header.size_kb << 10 ) ) >> 4 ),
- fbms );
-
- /* Do not zero out the freed block, because it might
- * be the one containing librm, in which case we're
- * going to have severe problems the next time we use
- * DBG() or, failing that, call get_memsizes().
- */
- }
+ /* Update our hidden memory region map */
+ hide_basemem();
}
projects / thirdparty / ipxe.git / commitdiff
