Commit 1b5aeebf authored by Lu Baolu's avatar Lu Baolu Committed by Ingo Molnar
Browse files

x86/earlyprintk: Add support for earlyprintk via USB3 debug port



Add support for earlyprintk by writing debug messages to the
USB3 debug port. Users can use this type of early printk by
specifying the kernel parameter of "earlyprintk=xdbc". This
gives users a chance of providing debugging output.

The hardware for USB3 debug port requires DMA memory blocks.
This requires to delay setting up debugging hardware and
registering boot console until the memblocks are filled.
Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-usb@vger.kernel.org
Link: http://lkml.kernel.org/r/1490083293-3792-4-git-send-email-baolu.lu@linux.intel.com

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent aeb9dd1d
......@@ -989,6 +989,7 @@
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
earlyprintk=pciserial,bus:device.function[,baudrate]
earlyprintk=xdbc[xhciController#]
earlyprintk is useful when the kernel crashes before
the normal console is initialized. It is not enabled by
......
......@@ -17,6 +17,7 @@
#include <asm/intel-mid.h>
#include <asm/pgtable.h>
#include <linux/usb/ehci_def.h>
#include <linux/usb/xhci-dbgp.h>
#include <linux/efi.h>
#include <asm/efi.h>
#include <asm/pci_x86.h>
......@@ -381,6 +382,10 @@ static int __init setup_early_printk(char *buf)
if (!strncmp(buf, "efi", 3))
early_console_register(&early_efi_console, keep);
#endif
#ifdef CONFIG_EARLY_PRINTK_USB_XDBC
if (!strncmp(buf, "xdbc", 4))
early_xdbc_parse_parameter(buf + 4);
#endif
buf++;
}
......
......@@ -70,6 +70,7 @@
#include <linux/tboot.h>
#include <linux/jiffies.h>
#include <linux/usb/xhci-dbgp.h>
#include <video/edid.h>
#include <asm/mtrr.h>
......@@ -1144,6 +1145,9 @@ void __init setup_arch(char **cmdline_p)
memblock_set_current_limit(ISA_END_ADDRESS);
memblock_x86_fill();
if (!early_xdbc_setup_hardware())
early_xdbc_register_console();
reserve_bios_regions();
if (efi_enabled(EFI_MEMMAP)) {
......
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