[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] isapc: Shadow ISA BIOS by default
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH] isapc: Shadow ISA BIOS by default |
Date: |
Fri, 12 Oct 2012 11:29:47 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-10-08 20:52, Anthony Liguori wrote:
> Jan Kiszka <address@hidden> writes:
>
>> On 2012-09-11 17:53, Jan Kiszka wrote:
>>> Our one and only BIOS depends on a writable shadowed BIOS in the ISA
>>> range. As we have no interface to control the write property, make that
>>> region writable by default.
>>>
>>> Signed-off-by: Jan Kiszka <address@hidden>
>>> ---
>>>
>>> This unbreaks isapc for TCG, and keep it working for KVM once it starts
>>> supporting read-only memslots.
>>>
>>> hw/pc_sysfw.c | 13 +++++++++----
>>> 1 files changed, 9 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/hw/pc_sysfw.c b/hw/pc_sysfw.c
>>> index b45f0ac..027d98a 100644
>>> --- a/hw/pc_sysfw.c
>>> +++ b/hw/pc_sysfw.c
>>> @@ -136,6 +136,7 @@ static void old_pc_system_rom_init(MemoryRegion
>>> *rom_memory)
>>> {
>>> char *filename;
>>> MemoryRegion *bios, *isa_bios;
>>> + void *isa_bios_ptr;
>>> int bios_size, isa_bios_size;
>>> int ret;
>>>
>>> @@ -167,19 +168,23 @@ static void old_pc_system_rom_init(MemoryRegion
>>> *rom_memory)
>>> g_free(filename);
>>> }
>>>
>>> - /* map the last 128KB of the BIOS in ISA space */
>>> + /* Shadow the last 128KB of the BIOS in ISA space as RAM -
>>> + * Seabios depends on this */
>>> isa_bios_size = bios_size;
>>> if (isa_bios_size > (128 * 1024)) {
>>> isa_bios_size = 128 * 1024;
>>> }
>>> isa_bios = g_malloc(sizeof(*isa_bios));
>>> - memory_region_init_alias(isa_bios, "isa-bios", bios,
>>> - bios_size - isa_bios_size, isa_bios_size);
>>> + memory_region_init_ram(isa_bios, "isa-bios", isa_bios_size);
>>> + vmstate_register_ram_global(isa_bios);
>>> memory_region_add_subregion_overlap(rom_memory,
>>> 0x100000 - isa_bios_size,
>>> isa_bios,
>>> 1);
>>> - memory_region_set_readonly(isa_bios, true);
>>> +
>>> + /* copy ISA rom image from top of the ROM */
>>> + isa_bios_ptr = memory_region_get_ram_ptr(isa_bios);
>>> + rom_copy(isa_bios_ptr, (uint32_t)(-isa_bios_size), isa_bios_size);
>>>
>>> /* map all the bios at the top of memory */
>>> memory_region_add_subregion(rom_memory,
>>>
>>
>> Ping. Or already queued?
>
> I've got it queued now. Thanks.
I'm withdrawing it: This breaks Windows 95 booting. For unknown reasons,
this nice OS decided to overwrite the F-segment during boot. That is
fine as long as it is properly protected. But it breaks under current
KVM and with the patch above for the isapc. So we need a firmware
interface to enable/disable write protection for this segment in isapc
mode, specifically as that machine targets these old OSes.
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux