Reading GRUB2 debug logs

Question

I want to see GRUB2 debug logs generated by grub_dprintf(), for example, at mmap.c:

  grub_dprintf ("mmap", "EFI memory region 0x%llx-0x%llx: %d\n",
        (unsigned long long) desc->physical_start,
        (unsigned long long) desc->physical_start
        + desc->num_pages * 4096, desc->type);

After some research, I found out the way to enable this log is by setting debug env variable at grub menu (I changed it on grub.cfg, probably am not supposed to do this)

set debug=all

How can I check the logs? The grub logs scrolled so fast during boot that it is hard to check. Perhaps there is a way to check the logs after kernel boots?

I am using CENTOS 7.

Sofiasofie

Is there a way to redirect GRUB2 debug output to the COM1 (ttyS0) ? – Ridings

Answer 1

Probably too late to be useful, but you could try:

set pager=1

Chipboard

I have it set, the errors still get scrolled immediately before grub goes into booting a system or to menu. – Fanciful