[Qemu-devel] CD-ROM Reading

["Mohammed Al-Saleh" <alsaleh@cs.unm.edu>]

Hi all;


Two methods to read from the CD-ROM depending on the following condition in 
the hw/ide.c file:

if (s->atapi_dma) {
        ide_atapi_cmd_read_dma(s, lba, nb_sectors, sector_size);
} else {
        ide_atapi_cmd_read_pio(s, lba, nb_sectors, sector_size);
}

in the first case (ide_atapi_cmd_read_dma), it is obvious how data will be 
read from the CD-ROM into an io_buffer and then to the RAM. But in the 
second case(ide_atapi_cmd_read_pio), it is obvious how that data will be 
read from the CD-ROM into an io_buffer, but it is not obvious how or when 
the data will written to the RAM. I know that cd_read_sector function (which 
is called from ide_atapi_cmd_reply_end) in ide.c will copy data from the CD-
ROM to an intermediate buffer, but I could not find out when this buffer is 
written to the RAM. All of what I can see is after reading data, 
ide_transfer_start and ide_set_irq are called, but then what? how data will 
go to the RAM? if data will be copied to the RAM implicitly through the 
interrupt, then where can I find the ultimate function that copies the data 
to the RAM.

Can any body answer my question? it will be very appreciated.

Thanks,

...Mohammed

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