Re: [Qemu-devel] [PATCH] [M25P80] Make sure not to overrun the internal data buffer.

[Jean-Christophe DUBOIS]

Le 30/12/2016 à 16:39, mar.krzeminski a écrit :
> I got some time, and reproduced the problem. Here are some logs with 
> m25p80 debugs:
> : decode_new_cmd: decoded new command:9f
> : decode_new_cmd: populated jedec code
> : decode_new_cmd: decoded new command:0
> : decode_new_cmd: decoded new command:0 //Getting flash Id in above 4 
> lines -> OK (but missing CS)
> Found sst25vf016b compatible flash device
> : decode_new_cmd: decoded new command:6 //Write enable, command 
> without payload, so it is ok
> : decode_new_cmd: decoded new command:1 //Write to status register, 
> guest sends data
> INFO: spi0.0: sst25vf016b (2048 Kbytes)
> INFO: spi0.0: mtd
>   .name = spi0.0,
>   .size = 0x200000 (2MiB)
>   .erasesize = 0x00001000 (4KiB)
>   .numeraseregions = 0
> Segmentation fault (core dumped) //Here probably guest try to send 
> some data
>
> The root cause why m25p80 enter strange state is that CS line is not 
> selected/deselected at all- there is missing debug from m25p80_cs.
> In spi transfer CS line (here qemu_irq) should be 0 before begin of 
> every message, and set after end of transmission.
> In case of simple WREN command you should see something like this:
> : m25p80_cs: deselect
> : decode_new_cmd: decoded new command:6
> : m25p80_cs: select
>
> Can you check spi controller model code?

I'll double check.

But why is the SPI memory/device even responding if CS is not set ?

> Thanks,
> Marcin