x86: reserve end-of-conventional-memory to 1MB on 32-bit (dedd04be) · Commits · 戴 / test

arch/x86/kernel/e820_32.c

+7 −20

Original line number	Diff line number	Diff line
		@@ -457,31 +457,18 @@ int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
		return -1;

		do {
		unsigned long long start = biosmap->addr;
		unsigned long long size = biosmap->size;
		unsigned long long end = start + size;
		unsigned long type = biosmap->type;
		u64 start = biosmap->addr;
		u64 size = biosmap->size;
		u64 end = start + size;
		u32 type = biosmap->type;

		/* Overflow in 64 bits? Ignore the memory map. */
		if (start > end)
		return -1;

		/*
		* Some BIOSes claim RAM in the 640k - 1M region.
		* Not right. Fix it up.
		*/
		if (type == E820_RAM) {
		if (start < 0x100000ULL && end > 0xA0000ULL) {
		if (start < 0xA0000ULL)
		add_memory_region(start, 0xA0000ULL-start, type);
		if (end <= 0x100000ULL)
		continue;
		start = 0x100000ULL;
		size = end - start;
		}
		}
		add_memory_region(start, size, type);
		} while (biosmap++, --nr_map);

		return 0;
		}

arch/x86/kernel/setup_32.c

+51 −13

Original line number	Diff line number	Diff line
		@@ -385,15 +385,60 @@ unsigned long __init find_max_low_pfn(void)
		return max_low_pfn;
		}

		#define BIOS_EBDA_SEGMENT 0x40E
		#define BIOS_LOWMEM_KILOBYTES 0x413

		/*
		* workaround for Dell systems that neglect to reserve EBDA
		* The BIOS places the EBDA/XBDA at the top of conventional
		* memory, and usually decreases the reported amount of
		* conventional memory (int 0x12) too. This also contains a
		* workaround for Dell systems that neglect to reserve EBDA.
		* The same workaround also avoids a problem with the AMD768MPX
		* chipset: reserve a page before VGA to prevent PCI prefetch
		* into it (errata #56). Usually the page is reserved anyways,
		* unless you have no PS/2 mouse plugged in.
		*/
		static void __init reserve_ebda_region(void)
		{
		unsigned int addr;
		addr = get_bios_ebda();
		if (addr)
		reserve_bootmem(addr, PAGE_SIZE, BOOTMEM_DEFAULT);
		unsigned int lowmem, ebda_addr;

		/* To determine the position of the EBDA and the */
		/* end of conventional memory, we need to look at */
		/* the BIOS data area. In a paravirtual environment */
		/* that area is absent. We'll just have to assume */
		/* that the paravirt case can handle memory setup */
		/* correctly, without our help. */
		#ifdef CONFIG_PARAVIRT
		if ((boot_params.hdr.version >= 0x207) &&
		(boot_params.hdr.hardware_subarch != 0)) {
		return;
		}
		#endif

		/* end of low (conventional) memory */
		lowmem = (unsigned short )__va(BIOS_LOWMEM_KILOBYTES);
		lowmem <<= 10;

		/* start of EBDA area */
		ebda_addr = (unsigned short )__va(BIOS_EBDA_SEGMENT);
		ebda_addr <<= 4;

		/* Fixup: bios puts an EBDA in the top 64K segment */
		/* of conventional memory, but does not adjust lowmem. */
		if ((lowmem - ebda_addr) <= 0x10000)
		lowmem = ebda_addr;

		/* Fixup: bios does not report an EBDA at all. */
		/* Some old Dells seem to need 4k anyhow (bugzilla 2990) */
		if ((ebda_addr == 0) && (lowmem >= 0x9f000))
		lowmem = 0x9f000;

		/* Paranoia: should never happen, but... */
		if ((lowmem == 0) \|\| (lowmem >= 0x100000))
		lowmem = 0x9f000;

		/* reserve all memory between lowmem and the 1MB mark */
		reserve_bootmem(lowmem, 0x100000 - lowmem, BOOTMEM_DEFAULT);
		}

		#ifndef CONFIG_NEED_MULTIPLE_NODES
		@@ -617,16 +662,9 @@ void __init setup_bootmem_allocator(void)
		*/
		reserve_bootmem(0, PAGE_SIZE, BOOTMEM_DEFAULT);

		/* reserve EBDA region, it's a 4K region */
		/* reserve EBDA region */
		reserve_ebda_region();

		/* could be an AMD 768MPX chipset. Reserve a page before VGA to prevent
		PCI prefetch into it (errata #56). Usually the page is reserved anyways,
		unless you have no PS/2 mouse plugged in. */
		if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
		boot_cpu_data.x86 == 6)
		reserve_bootmem(0xa0000 - 4096, 4096, BOOTMEM_DEFAULT);

		#ifdef CONFIG_SMP
		/*
		* But first pinch a few for the stack/trampoline stuff

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