Make printk() log to a buffer.
Tested on Qemu and Geode LX.
Benefits of this patch:
- printk() now works directly after printk_buffer_init(), even before
the serial port is set up.
- If all you want is a log, you don't have to bother with serial output.
- A payload can read and analyze the log.
- You can build on this and buffer log until serial is available, then
flush the messages buffered so far.
The printk buffer is configurable with a default-on Kconfig variable.
If you want to dump the buffer from the Qemu monitor after CAR has been
disabled, use this command:
memsave 0x90000 65536 memdump.bin
Signed-off-by: Carl-Daniel Hailfinger <email@example.com>
Acked-by: Peter Stuge <firstname.lastname@example.org>
Acked-by: Stefan Reinauer <email@example.com>
Acked-by: Marc Jones <firstname.lastname@example.org>