diff options
| author | Matt Fleming <matt.fleming@intel.com> | 2013-10-04 09:36:56 +0100 |
|---|---|---|
| committer | Matt Fleming <matt.fleming@intel.com> | 2013-10-28 18:09:58 +0000 |
| commit | 72548e836b0c4abbb652e791dee9c91203a9a4c6 (patch) | |
| tree | 2eead15738f173ed08ecbedc88adbb0bf2937022 /Documentation/kernel-parameters.txt | |
| parent | c158c3bf59951bbb44bd7ccca9e6665dfd1617c5 (diff) | |
| download | lwn-72548e836b0c4abbb652e791dee9c91203a9a4c6.tar.gz lwn-72548e836b0c4abbb652e791dee9c91203a9a4c6.zip | |
x86/efi: Add EFI framebuffer earlyprintk support
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>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 7f9d4f53882c..7a0f202d482e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -792,6 +792,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. earlyprintk= [X86,SH,BLACKFIN,ARM] earlyprintk=vga + earlyprintk=efi earlyprintk=xen earlyprintk=serial[,ttySn[,baudrate]] earlyprintk=serial[,0x...[,baudrate]] @@ -805,7 +806,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Append ",keep" to not disable it when the real console takes over. - Only vga or serial or usb debug port at a time. + Only one of vga, efi, serial, or usb debug port can + be used at a time. Currently only ttyS0 and ttyS1 may be specified by name. Other I/O ports may be explicitly specified @@ -819,8 +821,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Interaction with the standard serial driver is not very good. - The VGA output is eventually overwritten by the real - console. + The VGA and EFI output is eventually overwritten by + the real console. The xen output can only be used by Xen PV guests. |