Ok！ Just one more comment： After check the code flow, It's clear that the initialized memory region must be add to address space by calling memory_region_add_subregion in platform code before it can be accessed.
Best wishes ！ > 在 2017年1月5日，08:20，David Gibson <da...@gibson.dropbear.id.au> 写道： > >> On Wed, Jan 04, 2017 at 05:04:02PM +0000, Peter Maydell wrote: >>> On 4 January 2017 at 03:28, David Gibson <da...@gibson.dropbear.id.au> >>> wrote: >>>> On Tue, Jan 03, 2017 at 10:02:21PM +0800, 赵小强 wrote: >>>> Hi，david： >>>> >>>> To my understanding，what must be put in the realize function is >>>> code which depends on property values. What's the benefit of >>>> moving memory region initialization into realize function? I can >>>> not figure out, can you make some explanations? >>> >>> If nothing else it's better in realize() for consistency with other >>> devices. >> >> I'm not sure we're terribly consistent at all, really. My understanding >> was about the same as 赵小强 -- put stuff in init unless it has to >> go in realize because it depends on properties or might fail or >> has permanent effects on the simulation. >> Lots of existing devices do memory_region_init* calls in >> their init functions. >> We should probably write down our preferences somewhere, perhaps >> http://wiki.qemu.org/Documentation/QOMConventions >> >>> I'm not familiar enough with the details to be sure, but I also think >>> it's not safe in instance_init. Once memory regions are registered, >>> the device can potentially interact with other devices in the virtual >>> machine. realize() is sequenced to expect that, instance_init is not. >> >> Hmm, that doesn't sound right to me. The other devices will only >> interact with the memory regions when the calling code has >> finished doing the create/realize/map memory regions sequence -- >> an MR on its own doesn't do anything unless somebody maps it into >> an address space. > > Huh. Ok, I guess I was wrong. > > Alright, 赵小强, feel free to repost addressing just the other > comments and I'll merge. > > -- > David Gibson | I'll have my music baroque, and my code > david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ > | _way_ _around_! > http://www.ozlabs.org/~dgibson > 【来自网易邮箱的超大附件】 > 邮件带有附件预览链接，若您转发或回复此邮件时不希望对方预览附件，建议您手动删除链接。 > > signature.asc > 下载: http://u.163.com/t0/EPKVtbajXUHs > > 预览: http://u.163.com/t0/VUdsq6tC >
