Mikulas Patocka wrote:

I am reading FreeBSD ATA drivers because I want to use them as base for my
ATA driver and I found a total nonsence: in ata-dma.c in FreeBSD 4.8,
there is line

if (!((pci_read_config(parent,0x40,4)>>(ch->unit<<8))&0x4000)) {

        Hm, it should be (IMHO)
if (!((pci_read_config(parent,0x40,4)>>(ch->unit<<5))&0x4000))


That is incorrect too --- if ch->unit is 1, ch->unit<<5 is 32 and you
can't shift 32-bit integer by 32 bits.

My mistake. Configuration double-word at offset 64 (decimal) contain two word - one per unit. So, correct access to each word is
if (!((pci_read_config(parent,0x40,4)>>(ch->unit<<4))&0x4000))


My theory about source of error ('8' key just above '5') is void, of course.

        A smel bych, uz asi mimo konferenci, vedet, proc si pises vlastni ATA
ovladac ?

No, zatim to neni moc verejny projekt.

OK. Ja jen, ze se pred nekolika malo lety na MFF obhajoval projekt OS kde take meli vlastni ATA ovladace (a psal jsem je do znacne miry ja) - tak me jen tak napadlo, ze uz se zase pise nejaky podobny projekt nebo diplomka.



Sincerely


Dan


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