Re: [Fastboot] [PATCH] Reserving backup region for kexec basedcrashdumps.

From: Vivek Goyal
Date: Sun Jan 23 2005 - 04:26:16 EST

On Fri, 2005-01-21 at 16:43, Eric W. Biederman wrote:
> On deeper review your patch as it stands is incomplete. In particular
> you don't provide a way to either hardcode or dynamically set
> the area you are attempt to reserve to hold the backup region.

Well. Here is the new patch. This one steals the 640k from top of memory
region reserved for crash kernel.

A new command line parameter (crashbackup=) has been introduced for
crash dump kernels. This parameter specifies the location of backup
region from where to retrieve the backup data.

Thanks
Vivek



This patch adds support for reserving 640k memory as backup region as required
by crashdump kernel for x86.
---

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---

linux-2.6.11-rc1-root/Documentation/kernel-parameters.txt | 5 ++
linux-2.6.11-rc1-root/arch/i386/kernel/setup.c | 26 ++++++++++++--
linux-2.6.11-rc1-root/arch/i386/mm/discontig.c | 8 ++++
linux-2.6.11-rc1-root/include/linux/crash_dump.h | 1
linux-2.6.11-rc1-root/include/linux/kexec.h | 6 ++-
linux-2.6.11-rc1-root/kernel/crash_dump.c | 3 +
linux-2.6.11-rc1-root/kernel/kexec.c | 8 ++++
7 files changed, 54 insertions(+), 3 deletions(-)

diff -puN arch/i386/kernel/setup.c~crashdump-x86-reserve-640k-memory arch/i386/kernel/setup.c
--- linux-2.6.11-rc1/arch/i386/kernel/setup.c~crashdump-x86-reserve-640k-memory 2005-01-22 14:16:27.000000000 +0530
+++ linux-2.6.11-rc1-root/arch/i386/kernel/setup.c 2005-01-22 14:22:41.000000000 +0530
@@ -41,6 +41,7 @@
#include <linux/init.h>
#include <linux/edd.h>
#include <linux/kexec.h>
+#include <linux/crash_dump.h>
#include <video/edid.h>
#include <asm/apic.h>
#include <asm/e820.h>
@@ -51,7 +52,6 @@
#include <asm/io_apic.h>
#include <asm/ist.h>
#include <asm/io.h>
-#include <asm/crash_dump.h>
#include "setup_arch_pre.h"
#include <bios_ebda.h>

@@ -852,7 +852,20 @@ static void __init parse_cmdline_early (
}
}
#endif
-
+#ifdef CONFIG_CRASH_DUMP
+ /* crashbackup=size@addr specifies the location of backup
+ * region where, crashed kernel has stored some backup data.
+ */
+ else if (!memcmp(from, "crashbackup=", 12)) {
+ unsigned long size, base;
+ size = memparse(from+12, &from);
+ if (*from == '@') {
+ base = memparse(from+1, &from);
+ crashbackup_start = base;
+ crashbackup_end = base + size - 1;
+ }
+ }
+#endif
/*
* highmem=size forces highmem to be exactly 'size' bytes.
* This works even on boxes that have no highmem otherwise.
@@ -1159,6 +1172,14 @@ static unsigned long __init setup_memory
#ifdef CONFIG_KEXEC
if (crashk_res.start != crashk_res.end) {
reserve_bootmem(crashk_res.start, crashk_res.end - crashk_res.start + 1);
+
+#define CRASHDUMP_BACKUP_SZ 0xa0000
+ /* Steal 640K from top of reserved region for crash kernel */
+ if ((crashk_res.end - crashk_res.start) > CRASHDUMP_BACKUP_SZ) {
+ crashdumpk_res.end = crashk_res.end;
+ crashk_res.end = crashk_res.end - CRASHDUMP_BACKUP_SZ;
+ crashdumpk_res.start = crashk_res.end + 1;
+ }
}
#endif
return max_low_pfn;
@@ -1202,6 +1223,7 @@ legacy_init_iomem_resources(struct resou
request_resource(res, data_resource);
#ifdef CONFIG_KEXEC
request_resource(res, &crashk_res);
+ request_resource(res, &crashdumpk_res);
#endif
}
}
diff -puN arch/i386/mm/discontig.c~crashdump-x86-reserve-640k-memory arch/i386/mm/discontig.c
--- linux-2.6.11-rc1/arch/i386/mm/discontig.c~crashdump-x86-reserve-640k-memory 2005-01-22 14:16:27.000000000 +0530
+++ linux-2.6.11-rc1-root/arch/i386/mm/discontig.c 2005-01-22 14:40:30.000000000 +0530
@@ -29,6 +29,7 @@
#include <linux/highmem.h>
#include <linux/initrd.h>
#include <linux/nodemask.h>
+#include <linux/ioport.h>
#include <linux/kexec.h>
#include <asm/e820.h>
#include <asm/setup.h>
@@ -371,6 +372,13 @@ unsigned long __init setup_memory(void)
#ifdef CONFIG_KEXEC
if (crashk_res.start != crashk_res.end) {
reserve_bootmem(crashk_res.start, crashk_res.end - crashk_res.start + 1);
+#define CRASHDUMP_BACKUP_SZ 0xa0000
+ /* Steal 640K from top of reserved region for crash kernel */
+ if ((crashk_res.end - crashk_res.start) > CRASHDUMP_BACKUP_SZ) {
+ crashdumpk_res.end = crashk_res.end;
+ crashk_res.end = crashk_res.end - CRASHDUMP_BACKUP_SZ;
+ crashdumpk_res.start = crashk_res.end + 1;
+ }
}
#endif
return system_max_low_pfn;
diff -puN Documentation/kernel-parameters.txt~crashdump-x86-reserve-640k-memory Documentation/kernel-parameters.txt
--- linux-2.6.11-rc1/Documentation/kernel-parameters.txt~crashdump-x86-reserve-640k-memory 2005-01-22 14:16:27.000000000 +0530
+++ linux-2.6.11-rc1-root/Documentation/kernel-parameters.txt 2005-01-22 14:16:27.000000000 +0530
@@ -27,6 +27,7 @@ restrictions referred to are that the re
APM Advanced Power Management support is enabled.
AX25 Appropriate AX.25 support is enabled.
CD Appropriate CD support is enabled.
+ CRASHDUMP Crash Dump support is enabled.
DEVFS devfs support is enabled.
DRM Direct Rendering Management support is enabled.
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
@@ -345,6 +346,10 @@ running once the system is up.
[KNL] Reserve a chunk of physical memory to
hold a kernel to switch to with kexec on panic.

+ crashbackup=nn[KMG]@ss[KMG]
+ [KNL, CRASHDUMP] Specifies the location of crash data
+ backup region.
+
cs4232= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>

diff -puN include/linux/crash_dump.h~crashdump-x86-reserve-640k-memory include/linux/crash_dump.h
--- linux-2.6.11-rc1/include/linux/crash_dump.h~crashdump-x86-reserve-640k-memory 2005-01-22 14:16:27.000000000 +0530
+++ linux-2.6.11-rc1-root/include/linux/crash_dump.h 2005-01-22 14:16:27.000000000 +0530
@@ -15,6 +15,7 @@ extern void elf_kcore_store_hdr(char *,
#ifdef CONFIG_CRASH_DUMP
extern struct file_operations proc_vmcore_operations;
extern struct proc_dir_entry *proc_vmcore;
+extern unsigned long crashbackup_start, crashbackup_end;

extern ssize_t copy_oldmem_page(unsigned long, char *, size_t, int);
extern void crash_create_proc_entry(void);
diff -puN include/linux/kexec.h~crashdump-x86-reserve-640k-memory include/linux/kexec.h
--- linux-2.6.11-rc1/include/linux/kexec.h~crashdump-x86-reserve-640k-memory 2005-01-22 14:16:27.000000000 +0530
+++ linux-2.6.11-rc1-root/include/linux/kexec.h 2005-01-22 14:16:27.000000000 +0530
@@ -79,7 +79,7 @@ struct kimage {
unsigned long control_page;

/* Flags to indicate special processing */
- int type : 1;
+ unsigned int type : 1;
#define KEXEC_TYPE_DEFAULT 0
#define KEXEC_TYPE_CRASH 1
};
@@ -122,6 +122,10 @@ extern struct kimage *kexec_crash_image;
*/
extern struct resource crashk_res;

+/* Location of backup region to hold the crashdump kernel data.
+ */
+extern struct resource crashdumpk_res;
+
#else /* !CONFIG_KEXEC */
static inline void crash_kexec(void) { }
#endif /* CONFIG_KEXEC */
diff -puN kernel/crash_dump.c~crashdump-x86-reserve-640k-memory kernel/crash_dump.c
--- linux-2.6.11-rc1/kernel/crash_dump.c~crashdump-x86-reserve-640k-memory 2005-01-22 14:16:27.000000000 +0530
+++ linux-2.6.11-rc1-root/kernel/crash_dump.c 2005-01-22 14:16:27.000000000 +0530
@@ -15,6 +15,9 @@
#include <asm/io.h>
#include <asm/uaccess.h>

+/* Location of crashdump backup region if there is one. */
+unsigned long crashbackup_start, crashbackup_end;
+
/*
* Copy a page from "oldmem". For this page, there is no pte mapped
* in the current kernel. We stitch up a pte, similar to kmap_atomic.
diff -puN kernel/kexec.c~crashdump-x86-reserve-640k-memory kernel/kexec.c
--- linux-2.6.11-rc1/kernel/kexec.c~crashdump-x86-reserve-640k-memory 2005-01-22 14:16:27.000000000 +0530
+++ linux-2.6.11-rc1-root/kernel/kexec.c 2005-01-22 14:16:27.000000000 +0530
@@ -32,6 +32,14 @@ struct resource crashk_res = {
.flags = IORESOURCE_BUSY | IORESOURCE_MEM
};

+/* Location of the backup area for the crash dump kernel */
+struct resource crashdumpk_res = {
+ .name = "Crash Dump Backup",
+ .start = 0,
+ .end = 0,
+ .flags = IORESOURCE_BUSY | IORESOURCE_MEM
+};
+
/*
* When kexec transitions to the new kernel there is a one-to-one
* mapping between physical and virtual addresses. On processors
_