Am 09.07.2012 17:01, schrieb Anthony Liguori:
> On 07/09/2012 09:16 AM, Kevin Wolf wrote:
>> From: Markus Armbruster<arm...@redhat.com>
>>
>> Commit 5bbdbb46 moved it to block.c because "other geometry guessing
>> functions already reside in block.c". Device-specific functionality
>> should be kept in device code, not the block layer. Move it back.
>>
>> Disk geometry guessing is still in block.c. To be moved out in a
>> later patch series.
>>
>> Bonus: the floppy type used in pc_cmos_init() now obviously matches
>> the one in the FDrive. Before, we relied on
>> bdrv_get_floppy_geometry_hint() picking the same type both in
>> fd_revalidate() and in pc_cmos_init().
>>
>> Signed-off-by: Markus Armbruster<arm...@redhat.com>
>> Signed-off-by: Kevin Wolf<kw...@redhat.com>
>> diff --git a/hw/pc.c b/hw/pc.c
>> index c7e9ab3..e5e7647 100644
>> --- a/hw/pc.c
>> +++ b/hw/pc.c
>> @@ -335,10 +335,8 @@ void pc_cmos_init(ram_addr_t ram_size, ram_addr_t
>> above_4g_mem_size,
>> ISADevice *floppy, BusState *idebus0, BusState *idebus1,
>> ISADevice *s)
>> {
>> - int val, nb, nb_heads, max_track, last_sect, i;
>> - FDriveType fd_type[2] = { FDRIVE_DRV_NONE, FDRIVE_DRV_NONE };
>> - FDriveRate rate;
>> - BlockDriverState *fd[MAX_FD];
>> + int val, nb, i;
>> + FDriveType fd_type[2];
>
> This results in:
>
> CC i386-softmmu/hw/i386/../pc.o
> /home/anthony/git/qemu/hw/i386/../pc.c: In function ‘pc_cmos_init’:
> /home/anthony/git/qemu/hw/i386/../pc.c:339:16: error: ‘fd_type[1]’ may be
> used
> uninitialized in this function [-Werror=uninitialized]
> /home/anthony/git/qemu/hw/i386/../pc.c:339:16: error: ‘fd_type[0]’ may be
> used
> uninitialized in this function [-Werror=uninitialized]
> cc1: all warnings being treated as errors
>
> And GCC is right as:
>
>> static pc_cmos_init_late_arg arg;
>>
>> /* various important CMOS locations needed by PC/Bochs bios */
>> @@ -381,13 +379,8 @@ void pc_cmos_init(ram_addr_t ram_size, ram_addr_t
>> above_4g_mem_size,
>>
>> /* floppy type */
>> if (floppy) {
>> - fdc_get_bs(fd, floppy);
>> for (i = 0; i< 2; i++) {
>> - if (fd[i]) {
>> - bdrv_get_floppy_geometry_hint(fd[i],&nb_heads,&max_track,
>> -&last_sect, FDRIVE_DRV_NONE,
>> -&fd_type[i],&rate);
>> - }
>> + fd_type[i] = isa_fdc_get_drive_type(floppy, i);
>> }
>> }
>> val = (cmos_get_fd_drive_type(fd_type[0])<< 4) |
>
> This is an unconditional use of fd_type[0]. If floppy == NULL, this is
> dereferencing an uninitialized value.
>
> I'm not sure why the explicit initialization was removed...
Looks broken indeed. I just wonder why my gcc (or the buildbots) didn't
complain.
I dropped this patch from for-anthony, so you can give the pull request
another try.
Kevin
