[U-Boot-Users] ATA driver in U-Boot
I am not sure if this is off-topic, because I'm unsure of the division of labor.
Is there any reason that U-Boot needs ATA support compiled in? I ask because I'm trying to speed up booting on a small system with a hard drive. U-Boot waits for the devices to become available, scanning the ATA bus, before proceeding to load the Linux kernel. It appears to me that the kernel then does the same thing again, whereas if it went ahead and went straight to loading the kernel, it would give the drive another second or two to spin up and be ready for a bus scan.
Given that the kernel is being loaded out of flash (with all drivers compiled in), and that the only reference to the IDE drive that U-Boot really knows about is a commandline parameter passed to the kernel, would it cause any conspicuous problems to remove ATA support from U-Boot, or does the kernel depend on hardware information that U-Boot is providing (I notice there's a "U-Boot" section in the kernel config)?
Thanks, Victor Wren
On Fri, Oct 08, 2004 at 12:17:55PM -0800, Victor Wren wrote:
Given that the kernel is being loaded out of flash (with all drivers compiled in), and that the only reference to the IDE drive that U-Boot really knows about is a commandline parameter passed to the kernel, would it cause any conspicuous problems to remove ATA support from U-Boot, or does the kernel depend on hardware information that U-Boot is providing (I notice there's a "U-Boot" section in the kernel config)?
Victor,
It's been a little while since I looked at it, but I don't believe there is any reason why U-Boot needs to have the IDE/ATA stuff built-in unless U-Boot is going to use it. I'm pretty sure it doesn't communicate w/ the kernel about it (i.e. IDE) at all. Of course, YMMV... :-)
John
In message 41668573.16343.3D098D@localhost you wrote:
Is there any reason that U-Boot needs ATA support compiled in? I ask because
No, there is not. Which is the reason that this is an option which is configurable. And actually most of the boards don't enable it.
I'm trying to speed up booting on a small system with a hard drive. U-Boot waits for the devices to become available, scanning the ATA bus, before proceeding to load the Linux kernel. It appears to me that the kernel then does the same thing again, whereas if it went ahead and went straight to loading the kernel, it would give the drive another second or two to spin up and be ready for a bus scan.
If you enable ATA support in U-Boot you do this because you intend to use the disk in U-Boot. If this will never be the case then simply don't enable it. You get what you ask for.
Given that the kernel is being loaded out of flash (with all drivers compiled in), and that the only reference to the IDE drive that U-Boot really knows about is a commandline parameter passed to the kernel, would it cause any conspicuous problems to remove ATA support from U-Boot, or does the kernel depend on hardware information that U-Boot is providing (I notice there's a "U-Boot" section in the kernel config)?
The kernel does not know which boot loader was running. Just deiable ATA support (or anything else) in U-Boot if you don't need it.
Best regards,
Wolfgang Denk
participants (3)
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John W. Linville -
Victor Wren -
Wolfgang Denk