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Re: [PATCH] cdrom access patch


From: Vesa Jääskeläinen
Subject: Re: [PATCH] cdrom access patch
Date: Fri, 07 Mar 2008 17:37:26 +0200
User-agent: Thunderbird 2.0.0.12 (Windows/20080213)

Bean wrote:
Hi,

This patch use int 13 func 4B01 to detect cdrom. It also change the
name of the cd device to (hdN), where N is the bios drive number.

Hi Bean,

Have you tried to use EDD's functions to query for type of device?
(references are to EDD3 spec)

8.24 Get Device Parameters (FN 48h)
26 DWord Pointer to the Device Parameter Table Extension (DPTE)

8.24.3 Device Parameter Table Extension (DPTE)
10-11 Word BIOS selected hardware specific option flags

Bits 5 and 6; Removable device, ATAPI device.

This FN 48h can also be used to filter out PCI cards from ATA driver in case there is BIOS support for the device already. So use BIOS if there is BIOS handler for it, otherwise fall back to ATA driver.

I would prefer that CD's would be counted like (cd0) for first CD-ROM device, (cd1) for second CD-ROM device, ... and so on. I think it is OK to first allocate BIOS devices for CD's and after that use ATA driver for rest of them. Ata driver can of course be accessed with ata name too.

Thanks,
Vesa Jääskeläinen




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