From: Prarit Bhargava Date: Tue, 9 Sep 2008 13:56:08 +0000 (-0400) Subject: x86: fix memmap=exactmap boot argument X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d6be118a97ce51ca84035270f91c2bccecbfac5f;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git x86: fix memmap=exactmap boot argument When using kdump modifying the e820 map is yielding strange results. For example starting with BIOS-provided physical RAM map: BIOS-e820: 0000000000000100 - 0000000000093400 (usable) BIOS-e820: 0000000000093400 - 00000000000a0000 (reserved) BIOS-e820: 0000000000100000 - 000000003fee0000 (usable) BIOS-e820: 000000003fee0000 - 000000003fef3000 (ACPI data) BIOS-e820: 000000003fef3000 - 000000003ff80000 (ACPI NVS) BIOS-e820: 000000003ff80000 - 0000000040000000 (reserved) BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved) BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved) BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved) BIOS-e820: 00000000ff000000 - 0000000100000000 (reserved) and booting with args memmap=exactmap memmap=640K@0K memmap=5228K@16384K memmap=125188K@22252K memmap=76K#1047424K memmap=564K#1047500K resulted in: user-defined physical RAM map: user: 0000000000000000 - 0000000000093400 (usable) user: 0000000000093400 - 00000000000a0000 (reserved) user: 0000000000100000 - 000000003fee0000 (usable) user: 000000003fee0000 - 000000003fef3000 (ACPI data) user: 000000003fef3000 - 000000003ff80000 (ACPI NVS) user: 000000003ff80000 - 0000000040000000 (reserved) user: 00000000e0000000 - 00000000f0000000 (reserved) user: 00000000fec00000 - 00000000fec10000 (reserved) user: 00000000fee00000 - 00000000fee01000 (reserved) user: 00000000ff000000 - 0000000100000000 (reserved) But should have resulted in: user-defined physical RAM map: user: 0000000000000000 - 00000000000a0000 (usable) user: 0000000001000000 - 000000000151b000 (usable) user: 00000000015bb000 - 0000000008ffc000 (usable) user: 000000003fee0000 - 000000003ff80000 (ACPI data) This is happening because of an improper usage of strcmp() in the e820 parsing code. The strcmp() always returns !0 and never resets the value for e820.nr_map and returns an incorrect user-defined map. This patch fixes the problem. Signed-off-by: Prarit Bhargava Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 9af89078f7bb..66e48aa2dd1b 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -1203,7 +1203,7 @@ static int __init parse_memmap_opt(char *p) if (!p) return -EINVAL; - if (!strcmp(p, "exactmap")) { + if (!strncmp(p, "exactmap", 8)) { #ifdef CONFIG_CRASH_DUMP /* * If we are doing a crash dump, we still need to know