From ba3bbcb7fe5b4bb2e8be8dee46cfb637333471f6 Mon Sep 17 00:00:00 2001

From: Laszlo Ersek <lersek@redhat.com>

Date: Sat, 11 Jan 2014 17:59:52 +0100

Subject: [PATCH 02/22] Revert "pc: Disable the "use flash device for BIOS unless KVM" misfeature"

RH-Author: Laszlo Ersek <lersek@redhat.com>

Message-id: <1389463208-6278-3-git-send-email-lersek@redhat.com>

Patchwork-id: 56614

O-Subject: [RHEL-7.0 qemu-kvm PATCH 02/18] Revert "pc: Disable the "use flash device for BIOS unless KVM" misfeature"

Bugzilla: 1032346

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Amos Kong <akong@redhat.com>

RH-Acked-by: Andrew Jones <drjones@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

This reverts commit 23231f783d082bef74ba1d9fed6b07fdd058cb87.

RHEL-7 note -- I'll quote Markus' awesome original, RHEL-7-specific commit

message here:

> Use of a flash memory device for the BIOS was added in series "[PATCH

> v10 0/8] PC system flash support", commit 4732dca..1b89faf, v1.1.

>

> Flash vs. ROM is a guest-visible difference.  Thus, flash use had to

> be suppressed for machine types pc-1.0 and older.  This was

> accomplished by adding a dummy device "pc-sysfw" with property

> "rom_only":

>

> * Non-zero rom_only means "use ROM".  Default for pc-1.0 and older.

> * Zero rom_only means "maybe use flash".  Default for newer machines.

>

> Not only is the dummy device ugly, it was also retroactively added to

> the older machine types!  Fortunately, it's not guest-visible (thus no

> immediate guest ABI breakage), and has no vmstate (thus no immediate

> migration breakage).  Breakage occurs only if the user unwisely

> enables flash by setting rom_only to zero.  Patch review FAIL #1.

>

> Why "maybe use flash"?  Flash didn't work with KVM.  Therefore,

> rom_only=0 really means "use flash, except when KVM is enabled, use

> ROM".  This is a Bad Idea, because it makes enabling/ disabling KVM

> guest-visible.  Patch review FAIL #2.

>

> Aside: it also precludes migrating between KVM on and off, but that's

> not possible for other reasons anyway.

>

> Upstream commit 9953f88 killed the misfeature for new machine types.

> Upstream commit 9e1c2ec reverted the kill, but left a dead variable

> behind.  This is what's in RHEL-7 is before this patch.

>

> KVM has recently been made to support flash (KVM_CAP_READONLY_MEM),

> which permitted upstream QEMU to redo the flash vs. ROM switch

> properly (commit 338ea90..dafb82e).

This commit range is Jordan's series that this backport is all about.

> The required follow-up cleanup

> hasn't been committed, yet: Paolo's [PATCH v2 0/3] Remove legacy sysfw

> code.

It has now, I'm including it in the series.

> Instead of backporting all that, I'm simply ripping out the flash

> feature.  ROM has been working just fine for us, and I don't think we

> should complicate RHEL-7 maintenance and support by having two ways to

> map BIOS, at least not without sufficient business reason.

The business reason seems to be OVMF...

> The result behaves just like upstream with the follow-up cleanup

> applied, except -pflash doesn't affect the BIOS mapping, but remains

> as it always was: it creates an unused drive.

... and for it we need -pflash to create the real thing.

Signed-off-by: Laszlo Ersek <lersek@redhat.com>

---

 hw/block/pc_sysfw.c | 9 ---------

 1 file changed, 9 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/block/pc_sysfw.c |    9 ---------

 1 files changed, 0 insertions(+), 9 deletions(-)

diff --git a/hw/block/pc_sysfw.c b/hw/block/pc_sysfw.c

index 0bc5b7a..6149b20 100644

--- a/hw/block/pc_sysfw.c

+++ b/hw/block/pc_sysfw.c

@@ -36,7 +36,6 @@

 #define BIOS_FILENAME "bios.bin"

-#if 0   /* Disabled for Red Hat Enterprise Linux */

 typedef struct PcSysFwDevice {

     SysBusDevice busdev;

     uint8_t rom_only;

@@ -136,7 +135,6 @@ static void pc_system_flash_init(MemoryRegion *rom_memory,

     pc_isa_bios_init(rom_memory, flash_mem, size);

 }

-#endif  /* Disabled for Red Hat Enterprise Linux */

 static void old_pc_system_rom_init(MemoryRegion *rom_memory)

 {

@@ -193,7 +191,6 @@ static void old_pc_system_rom_init(MemoryRegion *rom_memory)

                                 bios);

 }

-#if 0   /* Disabled for Red Hat Enterprise Linux */

 /*

  * Bug-compatible flash vs. ROM selection enabled?

  * A few older machines enable this.

@@ -288,9 +285,3 @@ static void pcsysfw_register (void)

 type_init (pcsysfw_register);

-#else   /* Disabled for Red Hat Enterprise Linux */

-void pc_system_firmware_init(MemoryRegion *rom_memory)

-{

-    old_pc_system_rom_init(rom_memory);

-}

-#endif

-- 

1.7.1