Messages in this thread | | | Date | Fri, 2 Jun 2023 08:06:47 +0200 | Subject | Re: [PATCH v2] iscsi_ibft: Fix finding the iBFT under Xen Dom 0 | From | Juergen Gross <> |
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On 01.06.23 18:57, Dave Hansen wrote: > On 5/30/23 08:01, Ross Lagerwall wrote: >> Since firmware doesn't indicate the iBFT in the E820, add a reserved >> region so that it gets identity mapped when running as Dom 0 so that it >> is possible to search for it. Move the call to reserve_ibft_region() >> later so that it is called after the Xen identity mapping adjustments >> are applied. >> >> Finally, instead of using isa_bus_to_virt() which doesn't do the right >> thing under Xen, use early_memremap() like the dmi_scan code does. > > This is connecting Xen, iSCSI and x86. Some background here would be > *really* nice for dummies like me that deal heavily in only one of those > three. > > One or two sentences like this: > > Firmware can provide an iSCSI-specific table called the iBFT > which helps the OS boot from iSCSI devices. > > can go a long way for dummies like me. As could some background about > why this: > > ... add a reserved region so that it gets identity mapped when > running as Dom 0 so that it is possible to search for it. > > These are all English words, but off the top of my head, I have no idea > why reserved regions get identity mapped when running as Dom 0 or why > that makes it possible to search. > > The addresses and size here: > >> +#ifdef CONFIG_ISCSI_IBFT_FIND >> + /* Reserve 0.5 MiB to 1 MiB region so iBFT can be found */ >> + xen_e820_table.entries[xen_e820_table.nr_entries].addr = 0x80000; >> + xen_e820_table.entries[xen_e820_table.nr_entries].size = 0x80000; >> + xen_e820_table.entries[xen_e820_table.nr_entries].type = E820_TYPE_RESERVED; >> + xen_e820_table.nr_entries++; >> +#endif > > also appear to be conjured out of thin air.
I'd suggest to move the definitions of IBFT_START and IBFT_END from drivers/firmware/iscsi_ibft_find.c to include/linux/iscsi_ibft.h and use them here.
Juergen [unhandled content-type:application/pgp-keys][unhandled content-type:application/pgp-signature] | |