[U-Boot] Sharing code between Linux and bootloader (U-boot) ?
Hi,
Some bootloaders (like U-boot) support several HW devices: serial, network, NAND, USB, etc. most of which are also supported by Linux.
So the question is: is code shared? I mean, I understand that the drivers need to talk to the appropriate API, and such API could be different between Linux and U-boot. But putting that aside, would it be naive to imagine that some "core" functionality could be shared? Or would that part be so small it is not worth the effort?
Since many companies use both, U-boot and Linux, I would figure they try their best to optimize engineering resources and share code, right? In that case, I also wonder how do they share DT descriptions that right now are being stored in the Linux kernel tree.
We'd like to share code/DT for obvious reasons, what would you guys suggest?
Best regards,
Sebastian
On Fri, May 20, 2016 at 04:28:23PM +0200, Sebastian Frias wrote:
Hi,
Some bootloaders (like U-boot) support several HW devices: serial, network, NAND, USB, etc. most of which are also supported by Linux.
So the question is: is code shared? I mean, I understand that the drivers need to talk to the appropriate API, and such API could be different between Linux and U-boot. But putting that aside, would it be naive to imagine that some "core" functionality could be shared? Or would that part be so small it is not worth the effort?
Since many companies use both, U-boot and Linux, I would figure they try their best to optimize engineering resources and share code, right? In that case, I also wonder how do they share DT descriptions that right now are being stored in the Linux kernel tree.
We'd like to share code/DT for obvious reasons, what would you guys suggest?
So, in all cases, Linux is always the primary. In some cases in U-Boot we port drivers over (NAND is a good example here). In other cases, things are similar enough that it's having done it in one place it's easy enough to do it again in the other.
Hi Tom,
On 05/21/2016 03:41 AM, Tom Rini wrote:
On Fri, May 20, 2016 at 04:28:23PM +0200, Sebastian Frias wrote:
Hi,
Some bootloaders (like U-boot) support several HW devices: serial, network, NAND, USB, etc. most of which are also supported by Linux.
So the question is: is code shared? I mean, I understand that the drivers need to talk to the appropriate API, and such API could be different between Linux and U-boot. But putting that aside, would it be naive to imagine that some "core" functionality could be shared? Or would that part be so small it is not worth the effort?
Since many companies use both, U-boot and Linux, I would figure they try their best to optimize engineering resources and share code, right? In that case, I also wonder how do they share DT descriptions that right now are being stored in the Linux kernel tree.
We'd like to share code/DT for obvious reasons, what would you guys suggest?
So, in all cases, Linux is always the primary.
For drivers and DT?
In some cases in U-Boot we port drivers over (NAND is a good example here).
From your message, I get that first you write the driver for Linux and then port to U-boot, is that right?
I would have thought that the opposite way could be easier, since the U-boot driver could be simpler (maybe no DMA) w.r.t the one in Linux.
In other cases, things are similar enough that it's having done it in one place it's easy enough to do it again in the other.
So, basically people just do it again, duplicating code?
Best regards,
Sebastian
Sebastian Frias sf84@laposte.net writes:
Barebox shares a good amount of code. For example, when you look at SPI at AT24/AT25 you'll see that many things are almost identical.
participants (3)
-
Holger Schurig -
Sebastian Frias -
Tom Rini