Hi, Thanks all for your very valuable input. This seems to be an interesting topic that generates a lot of interest! I've updated my statement - does this reflect your views? "Given an unoptimised system based on embedded Linux with a clearly defined purpose - The amount of boot time it takes to reach that required state of functionality can be reduced by specialising the software stack to those needs. Specialisation may involve removing/deferring unrequired functionality/support and optimising required functionality." I've emphasised the focus of the statement to refer to a Linux based system and so by doing this optimisation then refers to the system as a whole including bootloaders, choice of filesystems, user space initialisation, etc. I've also defined boot time as the amount of time required to reach a useful state of functionality - in other words meeting only the needs of the application which provides the products purpose. By remove functionality/support - I mean removing support for device drivers not required and also removing unused functionality (which may be things like removing kallsyms, ipautoconfig, printk support, etc). And by 'optimise required functionality' - I think this can have a broad meaning and include system design decisions such as how userspace is initialised - e.g. the app could be the init process, optimising flash timings, using a more optimal filesystem, removing probes (if you know the hardware will always been there), etc. And I've tried to use relative terms rather than absolute terms - so the comparison is against an unoptimised system (e.g. perhaps a customer has a pre-provided BSP and they have little knowledge of how to optimise it and remove things via KConfig etc). Thanks, Andrew Murray On 22 October 2010 00:20, Andrew Murray <amurray@xxxxxxxxxxx> wrote: > Hello, > > I'm performing some research [for a CELF presentation] into reducing > boot time on embedded systems and would like to see if the embedded > community agree with the following statement as to why Linux > [arguably] takes so long in the first place for an unoptimised system: > > "Linux is general purpose, convenient and flexible. As it's general > purpose it's likely to contain un-required functionality which results > in more initialisation and a larger image size. As it's convenient and > flexible it will spent time discovering devices and verifying their > existence." > > Do you largely agree or disagree? > Also do you believe that boot time isn't the highest priority when it > comes to improving the kernel? > > Thanks, > > Andrew Murray > -- Andrew Murray, Embedded Linux Group MPC Data Limited e-mail: amurray@xxxxxxxxxxxxxx web: www.mpc-data.co.uk tel: +44 (0) 1225 710600 fax: +44 (0) 1225 710601 ddi: +44 (0) 1225 710665 MPC Data Limited is a company registered in England and Wales with company number 05507446 Registered Address: County Gate, County Way, Trowbridge, Wiltshire, BA14 7FJ VAT no: 850625238 The information in this email and in the attached documents is confidential and may be legally privileged. Any unauthorized review, copying, disclosure or distribution is prohibited and may be unlawful. It is intended solely for the addressee. Access to this email by anyone else is unauthorized. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. When addressed to our clients any opinions or advice contained in this email is subject to the terms and conditions expressed in the governing contract. -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
