Jan Kiszka <jan.kis...@siemens.com> writes:
> On 2012-10-08 20:52, Anthony Liguori wrote:
>> Jan Kiszka <jan.kis...@siemens.com> 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 <jan.kis...@siemens.com>
>>>> ---
>>>>
>>>> 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.
Ah, if it wasn't for a build break caused by one of the pull requests, I
would have pushed last night. Thanks for the heads up, I'll remove it
from my queue.
Is fw_cfg the right interface? I presume this is i440fx specific? How
does q35 handle this? Presumably there's a second window for the BIOS
mapping. There's got to be some way to do shadowing of it I would
think.
Regards,
Anthony Liguori
>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
> Corporate Competence Center Embedded Linux
