Re: [Qemu-devel] [PULL 08/27] ppc405_boards: Don't size flash memory to match backing image

[Peter Maydell]

On Mon, 11 Mar 2019 at 22:10, Markus Armbruster <address@hidden> wrote:
>
> Machine "ref405ep" maps its flash memory at address 2^32 - image size.
> Image size is rounded up to the next multiple of 64KiB.  Useless,
> because pflash_cfi02_realize() fails with "failed to read the initial
> flash content" unless the rounding is a no-op.
>
> If the image size exceeds 0x80000 Bytes, we overlap first SRAM, then
> other stuff.  No idea how that would play out, but useful outcomes
> seem unlikely.
>
> Map the flash memory at fixed address 0xFFF80000 with size 512KiB,
> regardless of image size, to match the physical hardware.
>
> Machine "taihu" maps its boot flash memory similarly.  The code even
> has a comment /* XXX: should check that size is 2MB */, followed by
> disabled code to adjust the size to 2MiB regardless of image size.
>
> Its code to map its application flash memory looks the same, except
> there the XXX comment asks for 32MiB, and the code to adjust the size
> isn't disabled.  Note that pflash_cfi02_realize() fails with "failed
> to read the initial flash content" for images smaller than 32MiB.
>
> Map the boot flash memory at fixed address 0xFFE00000 with size 2MiB,
> to match the physical hardware.  Delete dead code from application
> flash mapping, and simplify some.
>
> Cc: David Gibson <address@hidden>
> Signed-off-by: Markus Armbruster <address@hidden>
> Acked-by: David Gibson <address@hidden>
> Reviewed-by: Alex Bennée <address@hidden>
> Message-Id: <address@hidden>
> ---
>  hw/ppc/ppc405_boards.c | 36 ++++++++++++------------------------
>  1 file changed, 12 insertions(+), 24 deletions(-)

Hi; Coverity has just noticed a minor bug in this patch
(CID 1421917):

> diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
> index bb73d6d848..fe8e3cad12 100644
> --- a/hw/ppc/ppc405_boards.c
> +++ b/hw/ppc/ppc405_boards.c
> @@ -156,7 +156,7 @@ static void ref405ep_init(MachineState *machine)
>      target_ulong kernel_base, initrd_base;
>      long kernel_size, initrd_size;
>      int linux_boot;
> -    int fl_idx, fl_sectors, len;
> +    int len;
>      DriveInfo *dinfo;
>      MemoryRegion *sysmem = get_system_memory();
>
> @@ -177,20 +177,16 @@ static void ref405ep_init(MachineState *machine)
>                             &error_fatal);
>      memory_region_add_subregion(sysmem, 0xFFF00000, sram);
>      /* allocate and load BIOS */
> -    fl_idx = 0;
>  #ifdef USE_FLASH_BIOS
> -    dinfo = drive_get(IF_PFLASH, 0, fl_idx);
> +    dinfo = drive_get(IF_PFLASH, 0, 0);
>      if (dinfo) {
> -        BlockBackend *blk = blk_by_legacy_dinfo(dinfo);
> -
> -        bios_size = blk_getlength(blk);
> -        fl_sectors = (bios_size + 65535) >> 16;
> +        bios_size = 8 * MiB;
>          pflash_cfi02_register((uint32_t)(-bios_size),
>                                NULL, "ef405ep.bios", bios_size,
> -                              blk, 65536, fl_sectors, 1,
> +                              dinfo ? blk_by_legacy_dinfo(dinfo) : NULL,

This code is inside the "if (dinfo)" condition, so testing again
here whether it is NULL is unnecessary.

> +                              64 * KiB, bios_size / (64 * KiB), 1,
>                                2, 0x0001, 0x22DA, 0x0000, 0x0000, 0x555, 
> 0x2AA,
>                                1);
> -        fl_idx++;
>      } else
>  #endif
>      {
> @@ -425,7 +421,7 @@ static void taihu_405ep_init(MachineState *machine)
>      target_ulong kernel_base, initrd_base;
>      long kernel_size, initrd_size;
>      int linux_boot;
> -    int fl_idx, fl_sectors;
> +    int fl_idx;
>      DriveInfo *dinfo;
>
>      /* RAM is soldered to the board so the size cannot be changed */
> @@ -450,15 +446,11 @@ static void taihu_405ep_init(MachineState *machine)
>  #if defined(USE_FLASH_BIOS)
>      dinfo = drive_get(IF_PFLASH, 0, fl_idx);
>      if (dinfo) {
> -        BlockBackend *blk = blk_by_legacy_dinfo(dinfo);
> -
> -        bios_size = blk_getlength(blk);
> -        /* XXX: should check that size is 2MB */
> -        //        bios_size = 2 * 1024 * 1024;
> -        fl_sectors = (bios_size + 65535) >> 16;
> -        pflash_cfi02_register((uint32_t)(-bios_size),
> +        bios_size = 2 * MiB;
> +        pflash_cfi02_register(0xFFE00000,
>                                NULL, "taihu_405ep.bios", bios_size,
> -                              blk, 65536, fl_sectors, 1,
> +                              dinfo ? blk_by_legacy_dinfo(dinfo) : NULL,

Same here...

> +                              64 * KiB, bios_size / (64 * KiB), 1,
>                                4, 0x0001, 0x22DA, 0x0000, 0x0000, 0x555, 
> 0x2AA,
>                                1);
>          fl_idx++;
> @@ -491,14 +483,10 @@ static void taihu_405ep_init(MachineState *machine)
>      /* Register Linux flash */
>      dinfo = drive_get(IF_PFLASH, 0, fl_idx);
>      if (dinfo) {
> -        BlockBackend *blk = blk_by_legacy_dinfo(dinfo);
> -
> -        bios_size = blk_getlength(blk);
> -        /* XXX: should check that size is 32MB */
>          bios_size = 32 * MiB;
> -        fl_sectors = (bios_size + 65535) >> 16;
>          pflash_cfi02_register(0xfc000000, NULL, "taihu_405ep.flash", 
> bios_size,
> -                              blk, 65536, fl_sectors, 1,
> +                              dinfo ? blk_by_legacy_dinfo(dinfo) : NULL,

...and here.

> +                              64 * KiB, bios_size / (64 * KiB), 1,
>                                4, 0x0001, 0x22DA, 0x0000, 0x0000, 0x555, 
> 0x2AA,
>                                1);
>          fl_idx++;


Anybody feel like sending a patch?

thanks
-- PMM