[bikeshed] Re: Loading the ramdisk
- From: "WALTER LITWINCZYK (RIT Student)" <wtl4112@xxxxxxx>
- To: bikeshed@xxxxxxxxxxxxx
- Date: Sat, 28 Apr 2012 11:26:26 -0400
Let me amend that, you're physical address is 0x400 000
On Sat, Apr 28, 2012 at 11:25 AM, WALTER LITWINCZYK (RIT Student) <
wtl4112@xxxxxxx> wrote:
> You are correct, so you're loading routine would look something like the
> following:
>
> void* phys_address = 0x40 000;
> for (void* i = 0xE000 0000; i < (void *)(0xE000 0000 + file_sys_size); i
> += 4096, phys_address += 4096)
> {
> __phys_set_bit(phys_address);
> __virt_map_page(phys_address, i); // Check the order of the
> arguments I don't remember
> }
>
> (If this was D we could put underscores in the constants)
>
> As for the 508MiB, probably not, I still need some space to map PCI
> devices and I was hoping to put those at 0xF000 0000, leaving you 256MiB,
> but it's possible the PCI devices don't need 256MiB and I can probably get
> away with 124-128MiB for the PCI devices, but I wouldn't worry about it, if
> we have a 512MiB ramdisk we probably have other problems.
>
>
> On Sat, Apr 28, 2012 at 3:43 AM, David Larsen <dcl9934@xxxxxxx> wrote:
>
>> Hi Walter,
>>
>> So, I'll be merging master into my branch in a few days (and later my
>> branch into master (once I implement the syscalls)). I want to be sure that
>> I remember how we decided we should load the ramdisk into memory.
>>
>> I'll have FancyCat load the filesystem at 0x40 0000 in physical memory
>> and map the filesystem to 0xE000 0000 in virtual memory (after the kernel
>> heap).
>>
>> I'll use __phys_set_bit() to mark those pages as occupied and
>> __virt_map_page() to actually map 0x40 0000 physical -> 0xE000 0000
>> virtual. I'll have to use these in 4kb page increments.
>>
>> I'm going to leave the filesystem size at 120kb in the meantime, but I
>> should eventually be able to expand it to 508MiB, correct?
>>
>> Is there anything else I need to worry about?
>>
>>
>> Thanks,
>> David
>>
>>
>
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