Messages in this thread Patch in this message | | | From | John Ogness <> | Subject | Re: [PATCH printk v2 1/7] printk: Move buffer size defines | Date | Thu, 24 Nov 2022 13:44:29 +0106 |
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On 2022-11-24, Petr Mladek <pmladek@suse.com> wrote: >> Move the buffer size defines to console.h in preparation of adding a >> buffer structure. The new buffer structure will be embedded within >> struct console. Therefore console.h was chosen as the new home for >> these defines. > > The buffers are not embedded into struct console in this patchset. > Are they going to be added directly or via pointer, please?
By "embedded" I mean added directly. The buffers need to be available immediately and cannot be allocated or assigned dynamically. The console struct is generally defined by drivers with:
static struct console my_console = { ... };
I could think of no way to statically define the buffers but keep their sizes hidden.
> IMHO, it is always better to hide these implementation details > in an internal header or source file. It will be possible > if struct console contained on a pointer to the buffers.
The problem is not pointers, it is static definition (without knowing the size of the thing that is statically defined). The new thread/atomic consoles run in parallel, so they cannot share the single static buffer like we do now.
>> --- a/include/linux/console.h >> +++ b/include/linux/console.h >> @@ -122,6 +122,20 @@ static inline int con_debug_leave(void) >> #define CM_ERASE (2) >> #define CM_MOVE (3) >> >> +#ifdef CONFIG_PRINTK >> + >> +/* The maximum size of a formatted record (i.e. with prefix added per line) */ >> +#define CONSOLE_LOG_MAX 1024 >> + >> +#else >> + >> +#define CONSOLE_LOG_MAX 0 >> + >> +#endif >> + >> +/* The maximum size of a formatted extended record */ >> +#define CONSOLE_EXT_LOG_MAX 8192 > > It looks strange that we need the buffer for extended messages > and not the normal one when !CONFIG_PRINTK. I can't find any reason > for this. It looks like a historic inconsistency.
Yes, it looked that way to me as well. I will move it under CONFIG_PRINTK for v3.
John
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