Use memory region map to discover the memory

kernel/mm/mregmap.h

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+/*
+Copyright 2025 Kamil Kowalczyk
+
+Redistribution and use in source and binary forms, with or
+without modification, are permitted provided that the following
+conditions are met:
+
+1. Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+“AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef _MM_MREGMAP_H
+#define _MM_MREGMAP_H
+
+#include <libk/types.h>
+#include <libk/bitmap.h>
+
+enum {
+  MREG_AVAIL_RAM  = 1,          /* available ram */
+  /* i386 PC */
+  MREG_I386_PC_RESERVED = 2,    /* reserved by hardware/firmware */
+  MREG_ACPI       = 3,          /* ACPI info */
+  MREG_MEM_HBRNT  = 4,          /* must be preserved in hibernation */
+  MREG_DEFCT_RMOD = 5,          /* defective ram modules */
+};
+
+struct mreg {
+  uptr_t start;
+  usize_t size;
+  int type;
+};
+
+#define MREGMAP_MAX   256
+
+struct mregmap {
+  struct mreg mregs[MREGMAP_MAX];
+  byte_t bm_mem[MREGMAP_MAX];
+  struct bitmap bm;
+};
+
+void mregmap_init(void);
+struct mregmap *mregmap_get(void);
+bool_t mregmap_add_region(struct mreg *mreg);
+struct mreg *mregmap_first_avail(void);
+
+#endif // _MM_MREGMAP_H