[PATCH v2] qemu: fast boot when linuxboot optionrom is used - SeaBIOS

26 Nov 2018

Speed up the boot phase when qemu uses "linuxboot" optionrom
(qemu -kernel) and the boot-menu is not required.
Under these conditions we can skip the setup of devices and VGA,
because they will be initialized (if they are required) during
the Linux boot phase.
Following the time measured between SeaBIOS entry point and
"linuxboot" entry point:
* Before this patch
  qemu -kernel  | qemu -vga none -kernel
  --------------+-----------------------
  53.5 msec     | 23.34 msec
* After this patch
  qemu -kernel  | qemu -vga none -kernel
  --------------+-----------------------
  12.82 msec    | 10.89 msec
Note: For the measuring, we used the default configuration disabling
debug messages (CONFIG_DEBUG_LEVEL=0) and applying Stephen's patch:
"tpm: Check for TPM related ACPI tables before attempting hw"
Signed-off-by: Stefano Garzarella sgarzare@redhat.com
---
 src/bootsplash.c  |  3 +++
 src/fw/paravirt.c | 10 ++++++++++
 src/fw/paravirt.h |  4 ++++
 src/optionroms.c  |  3 ++-
 src/post.c        |  3 +++
 5 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/bootsplash.c b/src/bootsplash.c
index 165c98d..0eda7f2 100644
--- a/src/bootsplash.c
+++ b/src/bootsplash.c
@@ -8,6 +8,7 @@
 #include "bregs.h" // struct bregs
 #include "config.h" // CONFIG_*
 #include "farptr.h" // FLATPTR_TO_SEG
+#include "fw/paravirt.h" // runningOnQEMUFastBoot
 #include "malloc.h" // free
 #include "output.h" // dprintf
 #include "romfile.h" // romfile_loadfile
@@ -39,6 +40,8 @@ call16_int10(struct bregs *br)
 void
 enable_vga_console(void)
 {
+    if(runningOnQEMUFastBoot())
+        return;
     dprintf(1, "Turning on vga text mode console\n");
     struct bregs br;
diff --git a/src/fw/paravirt.c b/src/fw/paravirt.c
index 0770c47..9e6e618 100644
--- a/src/fw/paravirt.c
+++ b/src/fw/paravirt.c
@@ -621,4 +621,14 @@ void qemu_cfg_init(void)
     if (nogfx && !romfile_find("etc/sercon-port")
         && !romfile_find("vgaroms/sgabios.bin"))
         const_romfile_add_int("etc/sercon-port", PORT_SERIAL1);
+
+    /*
+     * Enable QEMU fast boot if there is "linuxboot" optionrom and
+     * the boot menu is not required.
+     */
+    if ((romfile_find("genroms/linuxboot_dma.bin")
+        || romfile_find("genroms/linuxboot.bin"))
+        && !romfile_loadint("etc/show-boot-menu", 1)) {
+        PlatformRunningOn |= PF_QEMU_FB;
+    }
 }
diff --git a/src/fw/paravirt.h b/src/fw/paravirt.h
index a14d83e..3713bc2 100644
--- a/src/fw/paravirt.h
+++ b/src/fw/paravirt.h
@@ -9,6 +9,7 @@
 #define PF_QEMU     (1<<0)
 #define PF_XEN      (1<<1)
 #define PF_KVM      (1<<2)
+#define PF_QEMU_FB  (1<<3)
typedef struct QemuCfgDmaAccess {
     u32 control;
@@ -24,6 +25,9 @@ static inline int runningOnQEMU(void) {
     return CONFIG_QEMU || (
         CONFIG_QEMU_HARDWARE && GET_GLOBAL(PlatformRunningOn) & PF_QEMU);
 }
+static inline int runningOnQEMUFastBoot(void) {
+    return runningOnQEMU() && GET_GLOBAL(PlatformRunningOn) & PF_QEMU_FB;
+}
 static inline int runningOnXen(void) {
     return CONFIG_XEN && GET_GLOBAL(PlatformRunningOn) & PF_XEN;
 }
diff --git a/src/optionroms.c b/src/optionroms.c
index fc992f6..c312e91 100644
--- a/src/optionroms.c
+++ b/src/optionroms.c
@@ -8,6 +8,7 @@
 #include "bregs.h" // struct bregs
 #include "config.h" // CONFIG_*
 #include "farptr.h" // FLATPTR_TO_SEG
+#include "fw/paravirt.h" // runningOnQEMUFastBoot
 #include "hw/pci.h" // pci_config_readl
 #include "hw/pcidevice.h" // foreachpci
 #include "hw/pci_ids.h" // PCI_CLASS_DISPLAY_VGA
@@ -428,7 +429,7 @@ vgarom_setup(void)
 {
     int have_vga = 0;
-    if (! CONFIG_OPTIONROMS)
+    if (!CONFIG_OPTIONROMS || runningOnQEMUFastBoot())
         return;
dprintf(1, "Scan for VGA option rom\n");
diff --git a/src/post.c b/src/post.c
index f93106a..d1c2a54 100644
--- a/src/post.c
+++ b/src/post.c
@@ -126,6 +126,9 @@ interface_init(void)
 void
 device_hardware_setup(void)
 {
+    if(runningOnQEMUFastBoot())
+        return;
+
     usb_setup();
     ps2port_setup();
     block_setup();
-- 
2.19.1



    