5.2-CURRENT panic on startup after cvsup: probably recent ATA

[Randy Bush]

> On start:
> ata-slave: TIMEOUT - ATAPI_IDENTIFY retrying (3 retries left) LBA=0
> 
> Fatal trap 12: page fault while in kernel mode
> fault virtual address = 0x36
> fault code = supervisor read, page not present
> instruction pointer = 0x8:0xc0428bb3
> stack pointer = 0x10:0xc0821d0c
> frame pointer = 0x10:0xc0821d34
> code segment = base 0x0, limit 0xfffff, type 0x1b
>              = DPL 0, pres 1, def32 1, gran 1
> processor eflags = interrupt enabled, resume, IOPL = 0
> current process = 0 (swapper)
> kernel: type 12 trap, code=0
> Stopped at ata_getparam+0xad: movzbl 0x36(%edx),%eax
> 
> trace:
> ata_getparam(c406f4d8,a1,c406f400,c0821d60,c04290f1) at ata_getparam+0xad
> ata_identify_devices(c406f400,1,0,c0611590,c0821d80) at
> ata_identify_devices+0x61
> ata_boot_attach(0,0,c0821d80,c04b476f,0) at ata_boot_attach+0x2e
> run_interrupt_driven_config_hooks(0,81e000,81ec00,81e000,0) at
> run_interrupt_driven_config_hooks+0x1c
> mi_startup() at mi_startup+0xa0
> begin() at begin+0x2c

5.2-RELEASE mini ISO has generally same boot crash on thinkpad t40p
    ^^^^^^^

but it's a page write trap 12

and i had been keeping -CURRENT updated every day, or other day
at worst, to keep this kind of problem from being in the release.
:-(

randy