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authorjljusten <jljusten@6f19259b-4bc3-4df7-8a09-765794883524>2013-05-15 08:09:29 +0000
committerjljusten <jljusten@6f19259b-4bc3-4df7-8a09-765794883524>2013-05-15 08:09:29 +0000
commitbf23b44d926982dfc9ecc7785cea17e0889a9297 (patch)
treea7bd0757119d46c4b1a34b9433f90907c2f4f1df
parenta7615fa87528fad341a37880d36e95f16faca5d3 (diff)
downloadedk2-platforms-bf23b44d926982dfc9ecc7785cea17e0889a9297.tar.xz
OvmfPkg: describe debug messages in the README file
Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14364 6f19259b-4bc3-4df7-8a09-765794883524
-rw-r--r--OvmfPkg/README23
1 files changed, 20 insertions, 3 deletions
diff --git a/OvmfPkg/README b/OvmfPkg/README
index 0c0a81a670..2c8b51fc76 100644
--- a/OvmfPkg/README
+++ b/OvmfPkg/README
@@ -66,13 +66,30 @@ http://sourceforge.net/apps/mediawiki/tianocore/index.php?title=How_to_build_OVM
(qemu-system-x86_64 works for the IA32 firmware as well, of course.)
* Use the QEMU -L parameter to specify the directory where the bios.bin
file is located.
-* Optionally you can use the QEMU -serial command to capture the
- OVMF debug messages. For example: -serial file:serial.log
* The EFI shell is built into OVMF builds at this time, so it should
run automatically if a UEFI boot application is not found on the
removable media.
* On Linux, newer version of QEMU may enable KVM feature, and this might
cause OVMF to fail to boot. The QEMU '-no-kvm' may allow OVMF to boot.
+* Capturing OVMF debug messages on qemu:
+ - The default OVMF build writes debug messages to IO port 0x402. The
+ following qemu command line options save them in the file called
+ debug.log: '-debugcon file:debug.log -global isa-debugcon.iobase=0x402'.
+ - It is possible to revert to the original behavior, when debug messages were
+ written to the emulated serial port (potentially intermixing OVMF debug
+ output with UEFI serial console output). For this the
+ '-D DEBUG_ON_SERIAL_PORT' option has to be passed to the build command (see
+ the next section), and in order to capture the serial output qemu needs to
+ be started with eg. '-serial file:serial.log'.
+ - Debug messages fall into several categories. Logged vs. suppressed
+ categories are controlled at OVMF build time by the
+ 'gEfiMdePkgTokenSpaceGuid.PcdDebugPrintErrorLevel' bitmask (an UINT32
+ value) in the selected .dsc file. Individual bits of this bitmask are
+ defined in <MdePkg/Include/Library/DebugLib.h>. One non-default bit (with
+ some performance impact) that is frequently set for debugging is 0x00400000
+ (DEBUG_VERBOSE).
+ - The RELEASE build target ('-b RELEASE' build option, see below) disables
+ all debug messages. The default build target is DEBUG.
=== Build Scripts ===
@@ -86,7 +103,7 @@ $ OvmfPkg/build.sh -a X64 qemu
And to run a 64-bit UEFI bootable ISO image:
$ OvmfPkg/build.sh -a X64 qemu -cdrom /path/to/disk-image.iso
-To build a 32-bit OVMF without debug serial messages using GCC 4.5:
+To build a 32-bit OVMF without debug messages using GCC 4.5:
$ OvmfPkg/build.sh -a IA32 -b RELEASE -t GCC45
=== Network Support ===