OK a fix has been found.

It seems ahci_command() doesn't correctly handle the situation, where buffer == NULL. 
It sets one cmd->prdt[0] entry and the AHCI hardware will probably either try to access
NULL pointer or will just wait indefinitely on data. NULL pointer is used in ATAPI command
cdb_test_unit_ready() and any subsequent command will get stuck.

Not setting any prd entry seems to fix the problem. Patch looks like that (but I don't know 
how much clean solution is it). 

diff --git a/src/hw/ahci.c b/src/hw/ahci.c
index d45b430..fbe1cec 100644
--- a/src/hw/ahci.c
+++ b/src/hw/ahci.c
@@ -117,7 +117,7 @@ static int ahci_command(struct ahci_port_s *port_gf, int iswrite, int isatapi,
     cmd->prdt[0].baseu = 0;
     cmd->prdt[0].flags = bsize-1;

-    flags = ((1 << 16) | /* one prd entry */
+    flags = (((buffer?1:0) << 16) | /* one prd entry */
              (iswrite ? (1 << 6) : 0) |
              (isatapi ? (1 << 5) : 0) |
              (5 << 0)); /* fis length (dwords) */

If this code is OK I will send the patch in a new thread.

There may be similar problem for PATA/IDE controller, but I didn't test it yet.

Petr


Dne 14. 07. 22 v 6:36 Petr Cvek napsal(a):
> Hello,
> 
> I've tried to boot a coreboot supported machine (Kontron 986lcd-m) from CD and it hangs.
> 
> The drive is correctly identified (AHCI ATAPI).
> 
> Petr
> 
> Log follows:
> 
> Booting from DVD/CD...
> scsi_is_ready (drive=0x000f5820)
> disk_op d=0x000f5820 lba=0 buf=0x00000000 count=0 cmd=32
> AHCI/2: send cmd ...
> AHCI/2: ... intbits 0x1, status 0x50 ...
> AHCI/2: ... finished, status 0x50, OK
> disk_op d=0x000f5820 lba=17 buf=0x000067a8 count=1 cmd=2
> AHCI/2: send cmd ...
> handle_08
> handle_hwpic1 irq=1
> 
> ... repeats ...
> 
> handle_08
> handle_hwpic1 irq=1
> WARNING - Timeout at ahci_command:153!
> Boot failed: Could nothandle_08
> handle_hwpic1 irq=1
>  read from CDROM (code 0003)
> enter handle_18:
>   NULL
> Booting from Hard Disk...
> enter handle_13:
>    a=00000201  b=00000000  c=00000001  d=00000080 ds=0000 es=07c0 ss=9000
>   si=00000000 di=00000000 bp=00000000 sp=0000ffd6 cs=f000 ip=ca99  f=0202
> disk_op d=0x000f5870 lba=0 buf=0x00007c00 count=1 cmd=2
> AHCI/1: send cmd ...
> AHCI/1: ... intbits 0x1, status 0x50 ...
> AHCI/1: ... finished, status 0x50, OK
> ahci disk read, lba      0, count   1, buf 0x00007c00, rc 0
> Booting from 0000:7c00
> 
> ... continues with sata hdd ...
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