Re: [Qemu-devel] [PATCH v4] hw/pc: Support system flash memory with -pflash parameter

[Jordan Justen]

On Sat, Jul 23, 2011 at 15:26, Anthony Liguori <address@hidden> wrote:
> On 07/23/2011 05:06 PM, Jordan Justen wrote:
>>
>> On Sat, Jul 23, 2011 at 14:25, Anthony Liguori<address@hidden>
>>  wrote:
>>>
>>> On 07/23/2011 03:19 PM, Jordan Justen wrote:
>>>>
>>>> On Sat, Jul 23, 2011 at 08:51, Anthony Liguori<address@hidden>
>>>>  wrote:
>>>>>
>>>>> On 07/08/2011 02:37 PM, Jordan Justen wrote:
>>>>>>
>>>>>> If -pflash is specified and -bios is specified then pflash will
>>>>>> be mapped just below the system rom using hw/pflash_cfi01.c.
>>>>>>
>>>>>> If -pflash is specified on the command line, but -bios is
>>>>>> not specified, then 'bios.bin' will NOT be loaded, and
>>>>>> instead the -pflash flash image will be mapped just below
>>>>>> 4GB in place of the normal rom image.
>>>>>
>>>>> This is way too tied to the pc platform to be this generic.
>>>>>
>>>>> I think a better approach would be to default to having unit=0 of
>>>>> IF_PFLASH
>>>>> default to a read-only BDS that points to bios.bin.  -bios would just
>>>>> be
>>>>> a
>>>>> short cut to use a different file name but you should be able to
>>>>> override
>>>>> with -drive too.
>>>>>
>>>>> And to really simplify things, you could add a readonly flag to -bios
>>>>> such
>>>>> that you could do:
>>>>>
>>>>> -bios foo.img,readonly=off
>>>>>
>>>>> Which is what I think you're looking for semantically.
>>>>
>>>> There seemed to be some feedback on the list interested in preserving
>>>> a read-only firmware, and just adding a flash region.
>>>>
>>>> So, for example, the firmware could be read from a common system
>>>> location like is generally done with bios.bin today, and VM instance
>>>> specific flash region could still be added.
>>>
>>> You can have multiple flash regions.
>>
>> So, is your recommendation that we support N pflash images in
>> x86/x86-64?  Instance/index 0 is mapped just under 4GB, and the rest
>> follow below this?
>
> No.  There should be a flash device, pflash index 0 is fine, but it should
> be mapped under 4GB and also in the legacy BIOS space.
>
> This is the PC firmware flash.  By default it should be read-only and it
> should be created by using ${prefix}/share/bios.bin.  But it should be
> possible to override both the filename and the read-only flag.
>
> In terms of other flash devices, I don't think it's that simple.  Flash is
> tied to the mobo layout so I don't think index > 0 really makes sense unless
> you allow a specific mapping address.  I doubt that's terribly useful.

I think VM's have a different situation than real hardware.  I'm not
sure an all ROM or all flash decision will work well for qemu.  In
most cases it may work better to make a ROM image available just below
4GB, and add a flash image below this ROM.

This allows the qemu's firmware to be updated as usual in
${prefix}/share/bios.bin, but still allows a flash memory to be
available below this.  (The flash below the ROM could be used only for
storing UEFI variables.)

Otherwise when a new qemu is released along with a new firmware image,
the VM instance using writable flash will continue to use the old
firmware image.

-Jordan

>
> Regards,
>
> Anthony Liguori
>
>>
>> This seems like a good plan, although I can't see a usage for more
>> than 2 instances.
>>
>> -Jordan
>>
>>> You're introducing two modes.  In one mode, we emulate a flash device and
>>> expose it for the BIOS ROM.  In the second mode, we don't emulate a
>>> device
>>> but we expose the BIOS ROM based on a file in a shared read-only
>>> location.
>>>
>>> I'm suggesting always emulating a flash device, but by default make the
>>> device read-only and have it be loaded from a file in a shared read-only
>>> location.
>>>
>>> That means we have a single code path and a consistent view from a
>>> management tooling perspective.  IOW, management tools will always see
>>> that
>>> there is a BIOS block device, and they need to worry about making sure
>>> that
>>> BIOS block device is there.
>>>
>>>>
>>>> If the entire firmware is moved to a separate VM instance specific
>>>> flash, then firmware update also gets complicated.  It is no longer
>>>> just a matter of updating the qemu firmware package in your distro's
>>>> package management system.
>>>
>>> I think the bit your misunderstanding is that you should default the
>>> firmware to be created from a common file as a read-only device.
>>>
>>> Regards,
>>>
>>> Anthony Liguori
>>>
>>>>
>>>> What about taking your idea, but adding a second drive that would be
>>>> mapped just below the 1st if it is specified with -drive?
>>>>
>>>> Thanks,
>>>>
>>>> -Jordan
>>>>
>>>>>
>>>>> Regards,
>>>>>
>>>>> Anthony Liguori
>>>>>
>>>>>>
>>>>>> Signed-off-by: Jordan Justen<address@hidden>
>>>>>> Reviewed-by: Aurelien Jarno<address@hidden>
>>>>>
>>>>>
>>>>>
>>>>>> ---
>>>>>>  default-configs/i386-softmmu.mak   |    1 +
>>>>>>  default-configs/x86_64-softmmu.mak |    1 +
>>>>>>  hw/pc.c                            |  161
>>>>>> +++++++++++++++++++++++++++---------
>>>>>>  3 files changed, 125 insertions(+), 38 deletions(-)
>>>>>>
>>>>>> diff --git a/default-configs/i386-softmmu.mak
>>>>>> b/default-configs/i386-softmmu.mak
>>>>>> index 55589fa..8697cd4 100644
>>>>>> --- a/default-configs/i386-softmmu.mak
>>>>>> +++ b/default-configs/i386-softmmu.mak
>>>>>> @@ -21,3 +21,4 @@ CONFIG_PIIX_PCI=y
>>>>>>  CONFIG_SOUND=y
>>>>>>  CONFIG_HPET=y
>>>>>>  CONFIG_APPLESMC=y
>>>>>> +CONFIG_PFLASH_CFI01=y
>>>>>> diff --git a/default-configs/x86_64-softmmu.mak
>>>>>> b/default-configs/x86_64-softmmu.mak
>>>>>> index 8895028..eca9284 100644
>>>>>> --- a/default-configs/x86_64-softmmu.mak
>>>>>> +++ b/default-configs/x86_64-softmmu.mak
>>>>>> @@ -21,3 +21,4 @@ CONFIG_PIIX_PCI=y
>>>>>>  CONFIG_SOUND=y
>>>>>>  CONFIG_HPET=y
>>>>>>  CONFIG_APPLESMC=y
>>>>>> +CONFIG_PFLASH_CFI01=y
>>>>>> diff --git a/hw/pc.c b/hw/pc.c
>>>>>> index a3e8539..e25354f 100644
>>>>>> --- a/hw/pc.c
>>>>>> +++ b/hw/pc.c
>>>>>> @@ -41,6 +41,7 @@
>>>>>>  #include "sysemu.h"
>>>>>>  #include "blockdev.h"
>>>>>>  #include "ui/qemu-spice.h"
>>>>>> +#include "flash.h"
>>>>>>
>>>>>>  /* output Bochs bios info messages */
>>>>>>  //#define DEBUG_BIOS
>>>>>> @@ -957,70 +958,154 @@ void pc_cpus_init(const char *cpu_model)
>>>>>>      }
>>>>>>  }
>>>>>>
>>>>>> -void pc_memory_init(const char *kernel_filename,
>>>>>> -                    const char *kernel_cmdline,
>>>>>> -                    const char *initrd_filename,
>>>>>> -                    ram_addr_t below_4g_mem_size,
>>>>>> -                    ram_addr_t above_4g_mem_size)
>>>>>> +static void pc_isa_bios_init(ram_addr_t ram_offset, int ram_size)
>>>>>>  {
>>>>>> -    char *filename;
>>>>>> -    int ret, linux_boot, i;
>>>>>> -    ram_addr_t ram_addr, bios_offset, option_rom_offset;
>>>>>> -    int bios_size, isa_bios_size;
>>>>>> -    void *fw_cfg;
>>>>>> -
>>>>>> -    linux_boot = (kernel_filename != NULL);
>>>>>> +    int isa_bios_size;
>>>>>>
>>>>>> -    /* allocate RAM */
>>>>>> -    ram_addr = qemu_ram_alloc(NULL, "pc.ram",
>>>>>> -                              below_4g_mem_size + above_4g_mem_size);
>>>>>> -    cpu_register_physical_memory(0, 0xa0000, ram_addr);
>>>>>> -    cpu_register_physical_memory(0x100000,
>>>>>> -                 below_4g_mem_size - 0x100000,
>>>>>> -                 ram_addr + 0x100000);
>>>>>> -    if (above_4g_mem_size>      0) {
>>>>>> -        cpu_register_physical_memory(0x100000000ULL,
>>>>>> above_4g_mem_size,
>>>>>> -                                     ram_addr + below_4g_mem_size);
>>>>>> +    /* map the last 128KB of the BIOS in ISA space */
>>>>>> +    isa_bios_size = ram_size;
>>>>>> +    if (isa_bios_size>      (128 * 1024)) {
>>>>>> +        isa_bios_size = 128 * 1024;
>>>>>>      }
>>>>>> +    ram_offset = ram_offset + ram_size - isa_bios_size;
>>>>>> +    cpu_register_physical_memory(0x100000 - isa_bios_size,
>>>>>> +                                 isa_bios_size,
>>>>>> +                                 ram_offset | IO_MEM_ROM);
>>>>>> +}
>>>>>> +
>>>>>> +static int pc_system_rom_init(void)
>>>>>> +{
>>>>>> +    int ret;
>>>>>> +    int bios_size;
>>>>>> +    ram_addr_t bios_offset;
>>>>>> +    char *filename;
>>>>>>
>>>>>>      /* BIOS load */
>>>>>> -    if (bios_name == NULL)
>>>>>> +    if (bios_name == NULL) {
>>>>>>          bios_name = BIOS_FILENAME;
>>>>>> +    }
>>>>>>      filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
>>>>>>      if (filename) {
>>>>>>          bios_size = get_image_size(filename);
>>>>>>      } else {
>>>>>>          bios_size = -1;
>>>>>>      }
>>>>>> -    if (bios_size<= 0 ||
>>>>>> -        (bios_size % 65536) != 0) {
>>>>>> -        goto bios_error;
>>>>>> +
>>>>>> +    if (bios_size<= 0 || (bios_size % 65536) != 0) {
>>>>>> +        ret = -1;
>>>>>> +    } else {
>>>>>> +        bios_offset = qemu_ram_alloc(NULL, "pc.bios", bios_size);
>>>>>> +        ret = rom_add_file_fixed(bios_name, (uint32_t)(-bios_size),
>>>>>> -1);
>>>>>>      }
>>>>>> -    bios_offset = qemu_ram_alloc(NULL, "pc.bios", bios_size);
>>>>>> -    ret = rom_add_file_fixed(bios_name, (uint32_t)(-bios_size), -1);
>>>>>> +
>>>>>>      if (ret != 0) {
>>>>>> -    bios_error:
>>>>>>          fprintf(stderr, "qemu: could not load PC BIOS '%s'\n",
>>>>>> bios_name);
>>>>>>          exit(1);
>>>>>>      }
>>>>>> +
>>>>>>      if (filename) {
>>>>>>          qemu_free(filename);
>>>>>>      }
>>>>>> -    /* map the last 128KB of the BIOS in ISA space */
>>>>>> -    isa_bios_size = bios_size;
>>>>>> -    if (isa_bios_size>      (128 * 1024))
>>>>>> -        isa_bios_size = 128 * 1024;
>>>>>> -    cpu_register_physical_memory(0x100000 - isa_bios_size,
>>>>>> -                                 isa_bios_size,
>>>>>> -                                 (bios_offset + bios_size -
>>>>>> isa_bios_size) | IO_MEM_ROM);
>>>>>>
>>>>>> -    option_rom_offset = qemu_ram_alloc(NULL, "pc.rom", PC_ROM_SIZE);
>>>>>> -    cpu_register_physical_memory(PC_ROM_MIN_VGA, PC_ROM_SIZE,
>>>>>> option_rom_offset);
>>>>>> +    pc_isa_bios_init(bios_offset, bios_size);
>>>>>>
>>>>>>      /* map all the bios at the top of memory */
>>>>>>      cpu_register_physical_memory((uint32_t)(-bios_size),
>>>>>>                                   bios_size, bios_offset |
>>>>>> IO_MEM_ROM);
>>>>>>
>>>>>> +    return bios_size;
>>>>>> +}
>>>>>> +
>>>>>> +static void pc_system_flash_init(DriveInfo *pflash_drv, int rom_size)
>>>>>> +{
>>>>>> +    BlockDriverState *bdrv;
>>>>>> +    int64_t size;
>>>>>> +    target_phys_addr_t phys_addr;
>>>>>> +    ram_addr_t addr;
>>>>>> +    int sector_bits, sector_size;
>>>>>> +
>>>>>> +    bdrv = NULL;
>>>>>> +
>>>>>> +    bdrv = pflash_drv->bdrv;
>>>>>> +    size = bdrv_getlength(pflash_drv->bdrv);
>>>>>> +    sector_bits = 12;
>>>>>> +    sector_size = 1<<      sector_bits;
>>>>>> +
>>>>>> +    if ((size % sector_size) != 0) {
>>>>>> +        fprintf(stderr,
>>>>>> +                "qemu: -pflash size must be a multiple of 0x%x\n",
>>>>>> +                sector_size);
>>>>>> +        exit(1);
>>>>>> +    }
>>>>>> +
>>>>>> +    phys_addr = 0x100000000ULL - rom_size - size;
>>>>>> +    addr = qemu_ram_alloc(NULL, "system.flash", size);
>>>>>> +    DPRINTF("flash addr: 0x%lx\n", (int64_t)phys_addr);
>>>>>> +    pflash_cfi01_register(phys_addr, addr, bdrv,
>>>>>> +                          sector_size, size>>      sector_bits,
>>>>>> +                          4, 0x0000, 0x0000, 0x0000, 0x0000, 0);
>>>>>> +
>>>>>> +    if (rom_size == 0) {
>>>>>> +        pc_isa_bios_init(addr, size);
>>>>>> +    }
>>>>>> +}
>>>>>> +
>>>>>> +static void pc_system_firmware_init(void)
>>>>>> +{
>>>>>> +    int flash_present, rom_present;
>>>>>> +    int rom_size;
>>>>>> +    DriveInfo *pflash_drv;
>>>>>> +
>>>>>> +    pflash_drv = drive_get(IF_PFLASH, 0, 0);
>>>>>> +    flash_present = (pflash_drv != NULL);
>>>>>> +
>>>>>> +    /* Load rom if -bios is used or if -pflash is not used */
>>>>>> +    rom_present = ((bios_name != NULL) || !flash_present);
>>>>>> +
>>>>>> +    /* If rom is present, then it is mapped just below 4GB */
>>>>>> +    if (rom_present) {
>>>>>> +        rom_size = pc_system_rom_init();
>>>>>> +    } else {
>>>>>> +        rom_size = 0;
>>>>>> +    }
>>>>>> +
>>>>>> +    /* If flash is present, then it is mapped just below the rom, or
>>>>>> +     * just below 4GB when rom is not present. */
>>>>>> +    if (flash_present) {
>>>>>> +        pc_system_flash_init(pflash_drv, rom_size);
>>>>>> +    }
>>>>>> +}
>>>>>> +
>>>>>> +void pc_memory_init(const char *kernel_filename,
>>>>>> +                    const char *kernel_cmdline,
>>>>>> +                    const char *initrd_filename,
>>>>>> +                    ram_addr_t below_4g_mem_size,
>>>>>> +                    ram_addr_t above_4g_mem_size)
>>>>>> +{
>>>>>> +    int linux_boot, i;
>>>>>> +    ram_addr_t ram_addr, option_rom_offset;
>>>>>> +    void *fw_cfg;
>>>>>> +
>>>>>> +    linux_boot = (kernel_filename != NULL);
>>>>>> +
>>>>>> +    /* allocate RAM */
>>>>>> +    ram_addr = qemu_ram_alloc(NULL, "pc.ram",
>>>>>> +                              below_4g_mem_size + above_4g_mem_size);
>>>>>> +    cpu_register_physical_memory(0, 0xa0000, ram_addr);
>>>>>> +    cpu_register_physical_memory(0x100000,
>>>>>> +                 below_4g_mem_size - 0x100000,
>>>>>> +                 ram_addr + 0x100000);
>>>>>> +    if (above_4g_mem_size>      0) {
>>>>>> +        cpu_register_physical_memory(0x100000000ULL,
>>>>>> above_4g_mem_size,
>>>>>> +                                     ram_addr + below_4g_mem_size);
>>>>>> +    }
>>>>>> +
>>>>>> +    /* Initialize ROM or flash ranges for PC firmware */
>>>>>> +    pc_system_firmware_init();
>>>>>> +
>>>>>> +    option_rom_offset = qemu_ram_alloc(NULL, "pc.rom", PC_ROM_SIZE);
>>>>>> +    cpu_register_physical_memory(PC_ROM_MIN_VGA, PC_ROM_SIZE,
>>>>>> option_rom_offset);
>>>>>> +
>>>>>>      fw_cfg = bochs_bios_init();
>>>>>>      rom_set_fw(fw_cfg);
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>