Re: [PATCH v4 07/12] efi: passing kexec necessary efi data via setup_data

Matt Fleming
2013-11-27T10:17:47Z

On Wed, 27 Nov, at 12:52:37PM, Dave Young wrote:
> To make it more readable, I will change them like below:
>
> p = efi_runtime_map;
> md = efi_setup->map;
> for (i = 0; i < nr_efi_runtime_map; i++) {
> [...]
> md += 1;
> }

Actually, md++ is the canonical way to write this.

> >
> > > + efi_map_region_fixed(md);
> > > + size = md->num_pages << PAGE_SHIFT;
> > > + end = md->phys_addr + size;
> > > +
> > > + systab = (u64) (unsigned long) efi_phys.systab;
> > > + if (md->phys_addr <= systab && systab < end) {
> > > + systab += md->virt_addr - md->phys_addr;
> > > + efi.systab =
> > > + (efi_system_table_t *) (unsigned long) systab;
> > > + }
> > > + if (efi_runtime_map) {
> > > + memcpy(p, md, memmap.desc_size);
> > > + p += memmap.desc_size;
> > > + }
> >
> > Is this if () needed? Is it possible to enter the loop and have
> > 'efi_runtime_map' be NULL?
>
> Yes, it is needed. if efi_runtime_map kmalloc fails I only print error, do not
> return so kernel can still boot, just kexec on efi will not work that has been
> put in the error message.

OK. On second thought, is there any way to turn the above code into a
call to efi_save_runtime_map()? Because you've basically duplicated that
code and I can definitely envisage the two code paths fragmenting over
time, e.g. when someone makes changes to one but not the other.

--
Matt Fleming, Intel Open Source Technology Center