From: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx> /dev/oldmem provides the interface for us to access the "old memory" in the dump-capture kernel. Unfortunately, no one actually uses this interface. And this interface could actually cause some real problems if used on ia64 where the cached/uncached accesses are mixed. See the discussion from the link: https://lkml.org/lkml/2013/4/12/386. So Eric suggested that we should remove /dev/oldmem as an unused piece of code. Suggested-by: "Eric W. Biederman" <ebiederm at xmission.com> Signed-off-by: Zhang Yanfei <zhangyanfei at cn.fujitsu.com> Cc: Vivek Goyal <vgoyal at redhat.com> Cc: Dave Hansen <dave at sr71.net> Cc: "H. Peter Anvin" <hpa at zytor.com> Cc: Andrew Morton <akpm at linux-foundation.org> --- drivers/char/mem.c | 47 ----------------------------------------------- 1 files changed, 0 insertions(+), 47 deletions(-) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 1ccbe94..bbe8ab4 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -21,7 +21,6 @@ #include <linux/ptrace.h> #include <linux/device.h> #include <linux/highmem.h> -#include <linux/crash_dump.h> #include <linux/backing-dev.h> #include <linux/bootmem.h> #include <linux/splice.h> @@ -357,40 +356,6 @@ static int mmap_kmem(struct file *file, struct vm_area_struct *vma) } #endif -#ifdef CONFIG_CRASH_DUMP -/* - * Read memory corresponding to the old kernel. - */ -static ssize_t read_oldmem(struct file *file, char __user *buf, - size_t count, loff_t *ppos) -{ - unsigned long pfn, offset; - size_t read = 0, csize; - int rc = 0; - - while (count) { - pfn = *ppos / PAGE_SIZE; - if (pfn > saved_max_pfn) - return read; - - offset = (unsigned long)(*ppos % PAGE_SIZE); - if (count > PAGE_SIZE - offset) - csize = PAGE_SIZE - offset; - else - csize = count; - - rc = copy_oldmem_page(pfn, buf, csize, offset, 1); - if (rc < 0) - return rc; - buf += csize; - *ppos += csize; - read += csize; - count -= csize; - } - return read; -} -#endif - #ifdef CONFIG_DEVKMEM /* * This function reads the *virtual* memory as seen by the kernel. @@ -772,7 +737,6 @@ static int open_port(struct inode *inode, struct file *filp) #define aio_write_zero aio_write_null #define open_mem open_port #define open_kmem open_mem -#define open_oldmem open_mem static const struct file_operations mem_fops = { .llseek = memory_lseek, @@ -837,14 +801,6 @@ static const struct file_operations full_fops = { .write = write_full, }; -#ifdef CONFIG_CRASH_DUMP -static const struct file_operations oldmem_fops = { - .read = read_oldmem, - .open = open_oldmem, - .llseek = default_llseek, -}; -#endif - static const struct memdev { const char *name; umode_t mode; @@ -866,9 +822,6 @@ static const struct memdev { #ifdef CONFIG_PRINTK [11] = { "kmsg", 0644, &kmsg_fops, NULL }, #endif -#ifdef CONFIG_CRASH_DUMP - [12] = { "oldmem", 0, &oldmem_fops, NULL }, -#endif }; static int memory_open(struct inode *inode, struct file *filp) -- 1.7.1
