Re: RAMOOPS: few questions

[Marco Stornelli <marco.stornelli@gmail.com>]

Il 01/06/2010 21:32, Maxim Levitsky ha scritto:
> Hi,
> 
> I want to switch over my own patch that does more or less the same that
> this driver.
> 
> As I see this driver uses ioremap to reserve the memory.
> However, I have a question about how to tell kernel that specific memory
> region is reserved.
> 
> Well, I use now mem=... to do so, but this wastes space, because the
> region I need can't be near end of the RAM.
> 

Have you got any particular constraints?

> I tried to use 'memmap=20M$0x70000000' on kernel command line, but that
> just makes kernel reboot.
> I think its a bug though.
> 
> Also, does this driver dupms all kernel log or only panic/oops message?

It dumps all, but there's a fixed size for each dump, so you can see the
panic/oops information and the latest prints of the kernel before
panic/oops.

> My patch actually makes kernel store actual printk buffer in fixed
> location, thus it is very robust. It was rejected though in favour of
> solution you eventually implemented.
> 
> Also I would like to extend your driver to dump old contents of the ram
> buffer to kernel log, so one wouldn't worry about erasing in on next
> boot after crash.
> Don't know when I do that though.
> 

ramoops uses a circular buffer of fixed size to store more information.
The number of "dumps" depends on the region size of memory you use.

Regards,

Marco