Re: advice

[YH]

Hello,

Apologize for off topic questions. While I am working on a device driver 
in kernel 2.4.21, I need advices from kernel developers.

1. When the read() or write() is called from user applications, the 
driver can either have a static buffer with limited size or dynamic 
memory allocation (kmalloc).

The static buffer is simple and reliable, but limited buffer size to 
applications.

Personally, I would like to use dynamic kernel memory allocation 
(kmalloc), the question is whether it could be any issues (reliability) 
to frequently call kmalloc / kfree in a high speed device (100mpbs)?

2. Although there is a mechanism for user applications to access the 
driver through function call read(), write(), or ioctl(). Can the 
application passes a callback pointer to the driver in kernel space so 
that the driver can call the callback function when some special event 
is received. Or if there is a mechanism to let the driver to send a 
notification to the user application?

Thank you and appreciate your helps.

Jim

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