Re: [Qemu-devel] [PATCH 06/10] r2d: Flash memory creation is confused about size, mark FIXME

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 2/18/19 1:56 PM, Markus Armbruster wrote:
> pflash_cfi02_register() takes a size in bytes, a block size in bytes
> and a number of blocks.  r2d_init() passes FLASH_SIZE, 16 * KiB,
> FLASH_SIZE >> 16.  Does not compute: size doesn't match block size *
> number of blocks.  The latter happens to win.  I tried to find
> documentation on the physcial hardware, no luck.
> 
> For now, adjust the byte size passed to match the actual size created,
> and add a FIXME comment.
> 
> Cc: Magnus Damm <magnus.damm@gmail.com>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  hw/sh4/r2d.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/sh4/r2d.c b/hw/sh4/r2d.c
> index dcdb3728cb..ed18d1f351 100644
> --- a/hw/sh4/r2d.c
> +++ b/hw/sh4/r2d.c
> @@ -290,7 +290,14 @@ static void r2d_init(MachineState *machine)
>  
>      /* onboard flash memory */
>      dinfo = drive_get(IF_PFLASH, 0, 0);
> -    pflash_cfi02_register(0x0, NULL, "r2d.flash", FLASH_SIZE,
> +    /*
> +     * FIXME The code is confused about the size of the flash.  It
> +     * used to pass FLASH_SIZE bytes, in FLASH_SIZE >> 16 blocks of
> +     * 16KiB each, which does not compute, but creates one of
> +     * FLASH_SIZE / 4 bytes anyway.  The current code does so too, but
> +     * whether it's the right size is anybody's guess.
> +     */
> +    pflash_cfi02_register(0x0, NULL, "r2d.flash", FLASH_SIZE / 4,
>                            dinfo ? blk_by_legacy_dinfo(dinfo) : NULL,
>                            16 * KiB, FLASH_SIZE >> 16,
>                            1, 4, 0x0000, 0x0000, 0x0000, 0x0000,

Good news: when you read (0x0000, 0x0000, 0x0000, 0x0000) pflash IDs,
that means the code uses the "Virt PFlash". IOW this is not a physical
model, since the guest obviously doesn't care about checking the flash
model.
The "VirtPFlash" only has 64KiB sectors.

I suggest we add a pflash_cfi02_create_virt(reduced args) helper to make
this obvious:

  pflash_cfi02_create_virt(paddr, name, size_bytes, mapping?).