On Thu, 31 Jul 2014 21:05:48 +0530 Vasant Hegde
<hegdevas...@linux.vnet.ibm.com> wrote:
> Platforms like IBM Power Systems supports service processor
> assisted dump. It provides interface to add memory region to
> be captured when system is crashed.
>
> During initialization/running we can add kernel memory region
> to be collected.
>
> Presently we don't have a way to get the log buffer base address
> and size. This patch adds support to return log buffer address
> and size.
>
> ...
>
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -10,6 +10,9 @@
> extern const char linux_banner[];
> extern const char linux_proc_banner[];
>
> +extern void *get_log_buf_addr(void);
> +extern u32 get_log_buf_len(void);
> +
> static inline int printk_get_level(const char *buffer)
> {
> if (buffer[0] == KERN_SOH_ASCII && buffer[1]) {
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 13e839d..4049f7b 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -270,6 +270,18 @@ static char __log_buf[__LOG_BUF_LEN]
> __aligned(LOG_ALIGN);
> static char *log_buf = __log_buf;
> static u32 log_buf_len = __LOG_BUF_LEN;
>
> +/* Return log buffer address */
> +void *get_log_buf_addr(void)
> +{
> + return log_buf;
> +}
> +
> +/* Return log buffer size */
> +u32 get_log_buf_len(void)
> +{
> + return log_buf_len;
> +}
> +
> /* human readable text of the record */
> static char *log_text(const struct printk_log *msg)
> {
Looks OK to me, although I think log_buf_addr_get() and
log_buf_len_get() would be better names. The kernel uses some
big-endian names and some little-endian-names and some middle-endian
names. It's all rather a mess. These symbols are already big-endian
(ie: decreasing significance):
log_buf -> addr -> get
log_buf -> len -> get
The world wouldn't end if we simply made log_buf and log_buf_len global
symbols. The pros and cons are all minor.
It's probably better to make get_log_buf_addr() tell the truth and
return a char *.
Please include this in whatever tree carries "powerpc/powernv:
Interface to register/unregister opal dump region".
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