1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _X86_CRASH_RESERVE_H
3 #define _X86_CRASH_RESERVE_H
4
5 /* 16M alignment for crash kernel regions */
6 #define CRASH_ALIGN SZ_16M
7
8 /*
9 * Keep the crash kernel below this limit.
10 *
11 * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
12 * due to mapping restrictions.
13 *
14 * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
15 * the upper limit of system RAM in 4-level paging mode. Since the kdump
16 * jump could be from 5-level paging to 4-level paging, the jump will fail if
17 * the kernel is put above 64 TB, and during the 1st kernel bootup there's
18 * no good way to detect the paging mode of the target kernel which will be
19 * loaded for dumping.
20 */
21 extern unsigned long swiotlb_size_or_default(void);
22
23 #ifdef CONFIG_X86_32
24 # define CRASH_ADDR_LOW_MAX SZ_512M
25 # define CRASH_ADDR_HIGH_MAX SZ_512M
26 #else
27 # define CRASH_ADDR_LOW_MAX SZ_4G
28 # define CRASH_ADDR_HIGH_MAX SZ_64T
29 #endif
30
31 # define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
32
33 static inline unsigned long crash_low_size_default(void)
34 {
35 #ifdef CONFIG_X86_64
36 return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
37 #else
38 return 0;
39 #endif
40 }
41
42 #define HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
43
44 #endif /* _X86_CRASH_RESERVE_H */
45
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