earlyprintk=efi,keep will cause kernel hangs while freeing initmem like
below:
VFS: Mounted root (ext4 filesystem) readonly on device 254:2.
devtmpfs: mounted
Freeing unused kernel memory: 880K (ffffffff817d4000 - ffffffff818b0000)
It is caused by efi earlyprintk use __init function which will be freed
later. Such as early_efi_write is marked as __init, also it will use
early_ioremap which is init function as well.
To fix this issue, I added early initcall early_efi_map_fb which maps
the whole efi fb for later use. OTOH, adding a wrapper function
early_efi_map which calls early_ioremap before ioremap is available.
With this patch applied efi boot ok with earlyprintk=efi,keep console=efi
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Dave reported seeing the following incorrect output on his Thinkpad T420
when using earlyprintk=efi,
[ 0.000000] efi: EFI v2.00 by Lenovo
ACPI=0xdabfe000 ACPI 2.0=0xdabfe014 SMBIOS=0xdaa9e000
The output should be on one line, not split over two. The cause is an
off-by-one error when checking that the efi_y coordinate hasn't been
incremented out of bounds.
Reported-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
It's incredibly difficult to diagnose early EFI boot issues without
special hardware because earlyprintk=vga doesn't work on EFI systems.
Add support for writing to the EFI framebuffer, via earlyprintk=efi,
which will actually give users a chance of providing debug output.
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Jones <pjones@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
