Re: [Qemu-devel] [PATCH 2/2] scsi: esp: Improve consistency of RSTAT, RSEQ, and RINTR

[Mark Cave-Ayland]

On 29/11/2018 19:07, Guenter Roeck wrote:

>> I've now completed a boot test of all my SPARC32 OpenBIOS CDROM images with 
>> this
>> patch, and whilst it doesn't solve my NextSTEP issue, I don't see any obvious
>> regressions.
>>
>> Note that NetBSD SPARC32 tends to spit out the occasional "!TC on data xfer" 
>> message
>> to the console during periods of disk access, however that is something that 
>> has
>> always happened and isn't something new introduced by this patch.
>>
> 
> That may be because reading the interrupt status resets the TC bit.
> As mentioned above, I think it shouldn't do that. Just a wild guess, but
> it might be worth a try. Can you remove "s->rregs[ESP_RSTAT] &= ~STAT_TC;"
> from the ESP_RINTR case in esp_reg_read() and see what happens ?
> 
> [That may expose situations where STAT_TC _should_ be cleared but isn't,
>  so we may hit other problems when doing that.]

I've tried that, and over a number of boots it does seem to allow the boot to 
get
further: with this change I'd say around 95% of the time NextSTEP now gets past 
the
SCSI bus enumeration and hangs at the point where it tries to mount the root 
filesystem.

Interestingly enough even if I comment out that line I still see the "!TC on 
data
xfer" messages appearing on the NetBSD console...


ATB,

Mark.